Research Collection · 2020-02-15 · iii Acknowledgements This doctoral dissertation could never...

Research Collection

Doctoral Thesis

Syntheses and characterization of amphiphilic, water solublepoly(p-phenylene)s and high-Tg, tough poly(m-phenylene)s bySuzuki polycondensation

Author(s): Kandre, Ramchandra Maruti

Publication Date: 2007

Permanent Link: https://doi.org/10.3929/ethz-a-005467418

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DISS. ETH No. 17298

Syntheses and Characterization of Amphiphilic, Water Soluble

Poly(p-phenylene)s and High-Tg , Tough Poly(m-phenylene)s

by Suzuki Polycondensation

A dissertation submitted to the

SWISS FEDERAL INSTITUTE OF TECHNOLOGY

ETH ZURICH

for the degree of Doctor of Sciences

Presented by

Ramchandra Maruti Kandre

M.Sc., University of Pune

born May 9, 1978

citizen of India

accepted on the recommendation of

Prof. Dr. A. Dieter Schlüter, examiner

Prof. Dr. Paul Smith, co-examiner

Prof. Dr. Peter Walde, co-examiner

Zürich 2007

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iii

Acknowledgements

This doctoral dissertation could never be accomplished without the involvement of other

peoples in all forms of interaction, support, advice, technical help as well as motivations. First

and foremost, the greatest gratitude is addressed to Prof. Dr. A. Dieter Schlüter who provided

me the opportunity to pursue doctoral study in a world class research institutes initially in

Freien Universität Berlin and then ETH Zürich and his advice during whole project.

I would like to express my sincere thanks to all the people for their excellent collaboration

and helpful discussion on this project, especially to Dr. Kirill Feldman and Prof. Dr. Paul

Smith for a very fruitful cooperation for the development of scope of poly(meta-phenylene)s.

Prof. Peter Walde for spectroscopic investigation of poly-phenylenes and continuous support.

Kathrin Hametner and Prof. Dr. Detlef Günther for trace element analysis. Dr. S. Lee and

Prof. Dr. Nicholas D. Spencer for OWLS study.

Many thanks to Daniela Zehnder, Jutta Hass and Dr. Pamela Winchester for their

secretarial help and continuous support. I also want to thank to our departmental technical

staff in particular Mr. Martin Colussi for GPC measurements. Dr. Heinz Rüegger and Doris

Sutter for the NMR measurements. Oswald Greter for countless MALDI-TOF mass

spectrometric measurements. Dr. Walter Amrein and Rolf Häfliger for their continuous help

with EI-MS and MALDI measurements.

And also to all the group members with whom I had the pleasure of working together:

Prof. Afang Zhang, Dr. Dorina Opris, Dr. Chengmei Zhang, Dr. Prashant Sonar, Dr. Rahul

Nandurdikar, Dr. Trishool Namani, Dr. Junji Sakamoto, Dr. Dirk Schubert, Dr. Holger

Frauenrath, Mihaiela Stuparu, Edis Kasemi, Rabie Al-Hellani, Hakan Atasoy, Cindy

Münzenberg, Igor Zhun, Eike Jahnke, Jialong Yuan, Xu Rui, Lera Tomasic and Ding Yi.

I would like to thanks to my friend Dr. Oleg Lukin for the helpful discussions we had, for

giving me invaluable help and encouragement during some troublesome situations. Alexander

Ossenbach is thanked for helping translate the Summary section into the German language

and continuous support. Many thanks to my Indian friends, Sachin, Suresh, Deepak and

Ramesh for giving me help and courage during my troublesome situation. Dr. P. P.

Wadgaonkar for helpful discussions and continuous support.

I would like to express my sincere gratitude to my parents (respected Shri. Maruti Babu

Kandre and Sau. Jaynabai Kandre). I learnt lot of lessons of well disciplined and cultural life

from my parents. My elder sister Vandana as a guide throughout in my educational

achievements. Her husband Balbhim and their kids Puja, Ujjwalla and Vishwas made my life

iv

with full of fun. My younger brother Bhimrao, his wife Usha and their son Mohit for their

support. Many thanks to Kandre and Ghatule family for their support.

I am very thankful to my wife Manisha Kandre for her never ending Love, encouragement

and continuous support during my PhD and wonderful gift of baby girl “Vandita”. At the last

but not least, Sant Nirankari Baba Hardev Singh Ji Maharaj for their valuable philosophical

thoughts which are essential to become a good human being.

Table of contents v

TABLE OF CONTENTS

Acknowledgments iii

Summary ix

Zusammenfassung xi

1. Introduction

1.1. General considerations 1

1.2. Aim of the work 5

1.3. Literature survey 6

2. Synthesis and Characterization of Amphiphilically Equipped Poly(para-phenylene)s

2.1. Amphiphilic substituents 20

2.2. PPPs with alkyl and oligo(ethylene oxy) (OEO) chain 21

2.2.1. Synthesis of amphiphilic dibromo monomer 21

2.2.2. Synthesis of amphiphilic diiodo monomer 23

2.2.3. Synthesis of amphiphilic monomer with linear OEG chain 24

2.2.4. Synthesis of boronic ester 26

2.2.4.1. Synthesis of benzene diboronic acid ester 45 27

2.2.4.2. Synthesis of diboronic acid ester 48 28

2.2.5. Suzuki polycondensation 29

2.2.6. Determination of molecular weights 33

2.2.7. Synthesis of amphiphilic monomers 51 and 55 and their PPPs 35

2.2.7.1. Synthesis of amphiphilic monomer 51 35

2.2.7.2. Synthesis of chiral amphiphilic monomer 55 35

2.2.7.3. Synthesis of polymer 52 and 56 36

2.3. Synthesis of phosphonic acid functionalized monomer 60 and their PPPs

61 and 62 39

2.3.1. Synthesis of monomer 60 39


2.4. Amino functionalized first and second generation dendritic PPPs 41

2.4.1. Synthesis of the amino functionalized monomer 65 42

2.4.2. Attempts for desymmetrization of hydroquinone 44


2.4.4. Desymmetrization: The key step in monomer synthesis 48

Table of contents vi


2.4.6. An optical wavelength lightmode spectroscopy study of adsorbed

oligomer 84 53

2.5. Frechét type second generation (G-2) dendritic PPPs 54

2.5.1. Monomer synthesis 54


2.6. Determination of trace elements in polymeric materials 56

2.6.1. Ligand scrambling 56

2.6.2. Spectroscopic detection of Pd(0) by using ligand 95 57

2.6.3. Determination of trace elements by ICP-MS and Laser Ablation

ICP-MS 60

2.7. Optical properties of polymer 56

2.7.1. UV/VIS absorption properties of polymer 56 61

2.7.2. Fluorescence spectroscopy 66

3. Synthesis and Characterization of Poly(meta-phenylene)s (PMPs) by SPC

3.1. General considerations 69

3.2. PMPs carrying flexible alkoxy chains

3.2.1. Synthesis of meta-monomers carrying alkoxy chains 69


3.2.3. Determination of molecular weights 72

3.2.4. Synthesis of meta-monomer 108 76


3.3. Co-polymerization 81

3.4. PMPs carrying water soluble OEG chains

3.4.1. Synthesis of meta-monomers carrying water soluble OEG chains 83


3.4.3. Synthesis of meta-monomer carrying two water soluble OEG chains 86


3.5. Determination of trace elements by ICP-MS and Laser Ablation ICP-MS 88

3.6. Determination of plausible end groups in the PMPs synthesized 89

3.7. Optical Properties of polymer 101

3.7.1. UV/VIS absorption properties of polymer 101 91

3.7.2. Fluorescence spectroscopy 93

3.8. IR spectroscopy 94

Table of contents vii

3.9. Thermal, WAXS and mechanical properties of polymer 101 95

3.9.1. Thermal properties

3.9.1.1. Thermogravimetric analysis 95

3.9.1.2. Differential scanning calorimetry 96

3.9.2. X-ray scattering 97

3.9.3. Mechanical properties 98

4. Investigation on SPC of tetra substituted monomers with aryl boronic acid esters

4.1. Synthesis of polymers 127, 128 and 131

4.1.1. Synthesis of monomer 126 and 130 102


4.2. Synthesis of PPPs using rigid monomers

4.2.1. Synthesis of rigid monomers 105


4.3. Synthesis of PPPs using tetra-substituted monomers

4.3.1. Synthesis of tetra-substituted dibromo monomer 141 106

4.3.2. Synthesis of tetra-substituted dibromo monomer 145 107


4.3.4. Synthesis of a tetra alkyl substituted monomer 108


5. Experimental section

5.1. General 111

5.1.1. Preparative chromatographic method 111

5.1.2. Product analysis 111

5.2. Syntheses 113

5.2.1. General synthetic procedures 114

5.2.2. Synthesis of compounds of Chapter 2 115



5.3. Spectroscopic quantification of Pd impurities in polymer 101 162

6. References 166

Appendix 174

Curriculum Vitae 177

Table of contents viii

Summary/Zusammenfassung ix

Summary

This thesis reports the applicability of Suzuki polycondensation (SPC) to aryl dibromides

with amphiphilic substituents and novel developments of this polymerization method towards

meta-phenylenes. In the first part of this work several Suzuki-type amphiphilic dibromo

monomers were synthesized. Simple and very efficient synthetic strategies are presented to

access these monomers. All the monomers were obtained in purity exceeding 99%, which was

determined by high-resolution NMR spectroscopy (500 or 700 MHz) and micro analysis.

These amphiphilic monomers undergo SPC to give a series of new representatives of a novel

class amphiphilic poly(para-phenylene)s (PPPs) as shown in Scheme a. Molecular weights

were determined by SEC with conventional polystyrene calibration and also with universal

calibration. Results from the latter method indicate that the former one underestimates the true

molecular weights of these polymers. All polymers gave high molecular weight materials

with monomodular GPC curves and the results are comparable with known PPPs synthesized

by this polymerization method.

Br

OR1

BBO

O O

OPd[P(p-tolyl)3]3 OR1

+NaHCO3

THF/H2O80 °C / 4 d

R1 = alkyl chains

Br

R2O

OR1OR1

R2O R2O R2O

n

R2 = linear or branched OEO chains

Poly(para -phenylene)s

~ 90%

Scheme a: General scheme for the synthesis of poly(para-phenylene)s. First steps towards the synthesis of amino-functionalized amphiphilic PPPs were

successfully done though molar masses are not yet in the range where they should be for the

aimed applications in the area of surface coatings.

Second part of this thesis deals with the investigation of new class of polymeric materials,

poly(meta-phenylene)s (PMPs), that combines an outstanding processability and remarkable

materials properties. The primary goal of this part of the work was therefore to explore the

family of PMPs. Several meta-monomers carrying either alkoxy or oligo ethyleneoxy chains

were synthesized. These monomers were subjected to conventional SPC conditions to obtain

corresponding PMPs as shown in Scheme b. Several PMPs were synthesized as high

molecular weight materials.

Summary/Zusammenfassung x

n

Br

OR

Br

BBO

O O

OPd[P(p-tolyl)3]3

OR OR

OROR

+NaHCO3

THF/H2O80 °C / 4 d

R = alkoxy, linear or branched OEO chains

~ 90%

Poly(meta -phenylene)s Scheme b: General scheme for the synthesis of poly(meta-phenylene)s.

In the present thesis, some materials properties of a selected member of the PMPs family

was described in detail. The polymer found to exhibit a highly useful combination of

properties, including convenient processability, a high glass transition temperature, (Tg) and

outstanding toughness, i.e. capability to absorb mechanical energy - rivalling that of high-

performance polycarbonates (PC), but with improved resistance against environmental stress-

cracking, a faiblesse of the latter engineering polymer. The chemical structure of the selected

polymer was studied systematically and thus, may serve as a model for a new family of high-

performance materials.

Phosphorous incorporation during SPC is a known side reaction. Therefore, a quantitative

determination of trace elements in the polymers obtained by SPC was one of the targets of the

present thesis. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and laser ablation-

ICP-MS techniques were applied as sensitive methods to determine quantitatively trace

amounts of relevant elements. Several polymer samples were analyzed and the Pd content was

determined as low as 81±7 ppm and the P-content as low as 725±69 ppm.

Summary/Zusammenfassung xi

Zusammenfassung Die vorliegende Arbeit zeigt die Anwendbarkeit der Suzuki-Polykondensation (SPC) auf

aromatische Dibromide mit amphiphilen Substituenten und neue Fortschritte im Bereich der

Polymerisation von meta-Phenylenen. Der erste Teil der Arbeit zeigt einige Synthesen von

amphiphilen Dibromderivaten für die SPC. Einfache und hoch effiziente Synthesestrategien

wurden angewendet um diese Monomere zugänglich zu machen. Alle synthetisierten

Monomere waren, nach hochauflösender NMR (500 MHz oder 700 MHz) und nach

Mikroanalyse, zu mindestens 99% rein. Die Polymerisation der verschiedenen Monomere

führte zu einer Serie einer neuen Klasse amphiphiler Poly(para-phenylen)e (PPPs) (Schema

a). Die Molmassen wurden mit GPC sowohl über Polystyrolkalibrierung als auch

Universalkalibrierung bestimmt. Die Molmassen bestimmt über die Universalkalibrieung

zeigen, dass die Polystyrolkalibrierung die tatsächlichen Molmassen der Polymere

unterschätzt. Alle Polymere ergaben hochmolekulare Materialien mit einheitlichen GPC-

Kurven. Die Ergebnisse stehen im Einklang mit bekannten PPPs via Suzuki-

Polykondensation.

Br

OR1

BBO

O O

OPd[P(p-tolyl)3]3 OR1

+NaHCO3

THF/H2O80 °C / 4 d

R1 = Alkyl

Br

R2O

OR1OR1

R2O R2O R2O

n

R2 = lineare oder verzweigte OEO-Ketten

Poly(para-phenylen)e

~ 90%

Schema a: Synthese von Poly(para-phenylen)en.

Erste Schritte zu aminofunktionalisierten amphiphilen PPPs sind erfolgreich durchgeführt

worden, allerdings konnten hier noch keine ausreichenden Molekulargewichte erzielt werden

um z. B. in der Oberflächenbeschichtung angewandt zu werden.

Der zweite Teil meiner Arbeit beschäftigt sich mit der Erforschung einer neuen Klasse von

Polymeren, den Poly(meta-phenylen)en (PMPs), die eine ausserordentlich gute

Verarbeitbarkeit und bemerkenswerte Materialeigenschaften in sich vereinigen. Das Hauptziel

dieser Arbeit liegt daher in der Erforschung und Untersuchung der Familie der PMPs.

Verschiedene meta-Monomere mit entweder Alkoxy- oder Oligo(ethylenoxy) sub-

stituenten sind zu diesem Zweck synthetisiert worden. Die Monomere wurden unter

konventionellen SPC-Bedingungen polymerisiert und die entsprechenden Polymere z. T. mit

hohen Molmassen erhalten (Schema b).

Summary/Zusammenfassung xii

n

Br

OR

Br

BBO

O O

OPd[P(p-to lyl)3]3

OR OR

OROR

+NaHCO3

THF/H2O80 °C / 4 d

R = Alkoxy, lineare oder verzweigte OEO-Ketten

~ 90%

Poly(meta-phenylen)e Schema b: Synthese von Poly(meta-phenylen)en. In der vorliegenden Arbeit wurden einige Materialeigenschaften ausgesuchter PMPs im Detail

beschrieben. Die Polymere zeigen eine sehr nützliche Kombination verschiedener

Eigenschaften wie einfache Verarbeitbarkeit, hohe Glasstemperatur (Tg) und eine hohe

Zähigkeit, d. h. die Fähigkeit mechanische Energie zu absorbieren - ähnlich der von

Hochleistungspolycarbonaten, aber mit einer höheren Spannungsrissbeständigkeit in

Flüssigkeiten, eine Schwäche der Polycarbonate. Die chemischen Strukturen von

ausgesuchten Polymeren wurden systematisch untersucht und können daher als Modell für

eine neue Familie von Hochleistungspolymeren genutzt werden.

Phosphoreinlagerungen im Polymer sind Resultat einer bekannten Nebenreaktion in der

Suzukipolykondensation. Ein weiteres Ziel dieser Arbeit war daher die Quantifizierung von

Spurenelementen in Polymeren die via SPC synthetisiert worden sind. Inductively Coupled

Plasma Mass Spectrometry (ICP-MS) und laser ablation-ICP-MS wurden als empfindliche

Methode genutzt um den Gehalt an relevanten Elementen zu bestimmen. Der Palladiumgehalt

eines Polymeren wurde zu 81±7 ppm und der Phosphorgehalt zu 725±69 ppm bestimmt.

Chapter 1 Introduction

1

1. Introduction 1.1. General considerations In the last century there has been considerable progress in the development of structurally

perfect polymers of different architectures and functionalities. Polymers with a poly(para-

phenylene) (PPP) backbone are considered as rigid-rod polymers. Their structure consists of a

linear sequence of phenylene repeat units, suggesting a high backbone stiffness. Rigid rod

polymers show unique behaviour as compared to flexible random coil polymers. Most

commercial synthetic polymers such as the various types of polyethylene are considered to be

flexible polymers. The random character of a coiled polymer reflects the fact that extremely large

numbers of conformational states of the backbone bonds are available, and this produces large

fluctuations in the overall size of the polymer. However, fully conjugated rigid rod polymers

having alternatively single and double bonds along their backbones emerge rapidly within the last

decade as an important material. Other material properties of this class of polymers arise from

their highly anisotropic shape,[1] optical, electrochemical and electrical properties leading to the

fabrication of optoelectronic and electronic devices,[2-4] photovoltaic cells[5] and biosensors.[6]

The thermal stability of this class of polymers made them even more attractive. These wide

applications make PPP attractive candidates but in the past their synthesis was not an easy task.

Unlike the established polyesters or polyamides, where the aromatic units are connected via

carboxylic esters or amides, requiring C-O bond and C-N bond formation, the synthesis of PPPs

involves the formation of C-C bonds which is much more difficult to achieve.

C C O C CO H

H

H

HO

O

C C NO

N

n

n

C C n

Polyester

Polyamide

Poly(para-phenylene)s

H H

O

Scheme 1: Chemical structures of some aromatic polymers.


2

In 1886 Goldschmidt reported the first PPP synthesis using the Wurtz-Fittig reaction (Scheme

2a). Thereafter, there were several attempts made to obtain these types of polymers. Earlier works

included Kovacic’s direct route (Scheme 2b) and the ICI researcher’s indirect route (Scheme 2c).

Both the approaches suffered serious drawbacks. Kovacic et al.[7] reported the oxidative

polymerization of benzene to prepare PPP using aluminium chloride as a Lewis acid catalyst and

copper chloride as an oxidant (Scheme 2b). The polymer obtained was a black material, which is

not to be expected given the proposed chemical structure. After Kovacic’s direct route, Ballard

and other ICI researchers[8] reported an indirect method where a precursor polymer, poly(5,6-

diacetoxy-1,4-cyclohex-2-ene), was synthesized first and then converted into the corresponding

polyphenylene by thermal elimination. By this indirect method, it was possible to obtain high

molecular weight polymers, although this route could not produce a uniform poly(para-

phenylene) without any defect. Another disadvantage of this method is that there were only a

small number of suitable precursor polymers available (Scheme 2c).

Br Br

Br Br

Wurtz-Fittig H Hn

H Hn

AlCl3

CuCl2

AcO OAc AcO OAc

n n

heat

a)

b)

c)Bu3Al

TiCl3

Scheme 2: Early attempts for the synthesis of poly(para-phenylene)s.[7, 8]

Consequently, despite attempts by Kovacic’s direct method and ICI researcher’s indirect

method, in 1978 Yamamoto reported the reaction between 1,4-dibromobenzene and Mg metal in

the presence of various Ni catalysts.[9] The polymer was exclusively para-linked and had a

degree of polymerization between 5 and 15 (Scheme 3a). Schlüter and co-workers tested the

applicability of the Yamamoto method to 1,4-dibromobenzene bearing flexible side chains in the

2- and 5-positions as shown in Scheme 3b. Although the PPP prepared had only 10-15 repeating

units, the material obtained was soluble in organic solvents which enabled complete analysis of

its structure and molecular weight. Among all these methods, Yamamoto’s approach was


3

considered most efficient because it was the only one that guaranteed the required straight, 1,4-

connection of benzene rings. The major disadvantages of this approach, however, were i) that one

could obtain only low molecular weight materials, ii) that it was difficult to maintaining a

stoichiometric balance of two functional groups during polymerization, iii) that it required

Grignard reaction conditions, and iv) Yamamoto himself proved that some termination takes

place in the course of the Ni-catalysed polycondensation reaction.

a)

b)

c)

Br Br

Br Br

Br Br

n

n

R

R

R

R

R

Rn

R

R

Br B(OH)2

R

R

Ni

Pd

Mg

n-BuLi

B(OCH3)3

n = 5-15

n= 10-15

n ~30

Ni

Mg

Scheme 3: Synthesis of PPPs: (a) Yamamoto route, (b) Yamamoto route with a modified

monomer (which carries alkyl side chains), and c) Suzuki polycondensation (SPC) involving AB-

type monomer

Two important factors needed to be considered to develop this class of polymers: a) high

coupling conversion and b) solubility. In the late eighties, Schlüter and co-workers reported for

the first time the synthesis of uniform PPPs without any defects.[10] They took 1,4-dibromo-2,5-

dialkylbenzene as starting material but then one of the bromo group was converted into boronic

acid to obtain an AB type monomer. They used boronic acids as Grignard analogues and applied

the Pd-catalysed Suzuki cross coupling (SCC) reaction to obtain soluble n-alkyl substituted PPPs

with up to 100 repeating units (Scheme 3c). A system of AA- and BB-type monomers with

various functional groups could then be introduced into the coupling reaction. Since then, the Pd-

catalyzed Suzuki polycondensation (SPC) of aryl halides and aryl boronic acids has been

developed as an important tool for the synthesis of polyarylenes and related polymers.[11] The

main advantages of this step growth polymerization reactions are: a) high regioselectivity of the


4

reaction, b) non toxic starting materials, c) easy separation of inorganic boron compounds, d)

insignificant effect of steric hindrance, e) application for a broad range of functional groups like

esters, nitro, amino and ether groups, f) easy use of the reaction both in aqueous as well as

heterogeneous reaction conditions, g) mild reaction conditions, and h) the high molecular weights

achieved.

Figure 1 is a comparison of the aromatic regions of the 13C NMR spectra of PPPs obtained

according to the Yamamoto and Suzuki polycondensation. While in the first spectrum (Figure 1a)

signals originated from end groups had considerable intensities, this was not so in the second case

(Figure 1b). This comparison shows that SPC is an improved method compared with the

Yamamoto procedure for the synthesis of polyarylenes and related polymers.[10]

Figure 1: Aromatic region of the 13C NMR spectrum of a particular PPP obtained by (a) the

modified Yamamoto route and (b) by Suzuki polycondensation (R = hexyl group).[10] The small

peaks indicated by arrows arise from carbon atoms present in the end groups.

However, the polymers so far synthesized by SPC used relatively expensive monomers,

catalysts and reaction conditions. In SPC reactions, two important factors need to be considered,

the nature of the catalyst and the chemical structure of the leaving group in the aryl halides. A

wide range of Pd (0) catalysts or precursors can be used for Suzuki-cross coupling reactions. For

example, Pd(PPh3)4 is the most commonly applied catalyst precursor. Ortho- and para-tolyl

ligands were also successfully used in SPC. Aryl bromides are the most often encountered

coupling partners in SPC. It was found recently that iodo compounds furnish higher molar mass

polymers than their bromo analoges (see 2.2.5). Furthermore, the cheap and commercially

available aryl chlorides, although successfully used in conventional SCC,[12] have not yet been

transferred to polymer chemistry.


5

1.2. Aim of the work The main aim of the work was to contribute to the synthesis and characterization of

amphiphilically equipped poly(para-phenylene)s which have the potential to segregate

lengthwise. The first goal of this thesis was to synthesize few amphiphilic model AA-type

dibromo monomers and BB-type aryl boronic acid esters, followed by optimization of the Suzuki

polycondensation reaction with these model monomers using a Pd-catalyst. There are only few

reports in the literature for the use of diiodo monomers in SPC. Usually, these monomers do not

yield higher molecular weight products than their dibromo analogs. One of the goal of this thesis

was therefore to compare the reactivity of the dibromo and diiodo monomers under SPC reaction

conditions.

So far SPC is a well known step growth polymerization reaction for the synthesis of linear as

well as branched poly(para-phenylene)s (PPPs). Aim of the second part of the present work was

to investigate whether poly(meta-phenylene)s (PMPs) can also be effectively prepared by this

method. Only a few reports described the synthesis of PMPs but most of them yield low

molecular weight materials only. The aim of the project was therefore to design and develop

simple synthetic strategies to prepare meta-monomers carrying flexible alkyl or oligo

ethyleneoxy chains and to subject them to SPC. The kinked structures of the resulting polymers

should not only impart enhanced processability to the polymer – as found for the related meta-

analogs of aromatic polyamides (aramids) and polyesters – but also are likely to permit

formation of highly amorphous materials. If high molar mass poly(meta-phenylene)s could be

achieved, then it was a logic further task of the present thesis to study their processability as well

as their general behaviours as new amorphous material.

SSC as well as SPC reactions are carried out using Pd(0) complexes as catalyst precursors

which typically carry stabilizing phosphine ligands. The catalytic cycle is believed to involve

Pd(II) species. It was reported before that side reactions can lead to the formation of phosphorus-

containing groups, not only as terminators but also as integral parts of the polymeric backbone.

The goal of this thesis was to determine by a quantitative analysis of the presence of trace

elements in the polymeric chain. The final goal of this thesis was to analyze the end groups in the

polymeric chain and to possibly gain insight into some mechanistic aspects of SPC.


6

1.3. Literature survey 1.3.1. Poly(para-phenylene)s

After the successful synthesis of alkyl-substituted PPPs in the late eighties, there have been

several reports describing the preparation and properties of PPPs with different substituents.[13, 14]

With a few exceptions, most of the reports have two things in common: a) use of bromo

monomers and b) presence of substituents (hydrophobic, hydrophilic or amphiphilic), which are

used to achieve better solubility. Herein, some of the more interesting reports are briefly

described.

Different amphiphilic dendronized PPPs were reported by Schlüter and co-workers.[15, 16] PPPs

1 and 2 formed stable monolayers at the air/water interface with the backbones arranged parallel

to the surface and the oligo (ethyleneoxy) chains dipping into the water phase. This finding was

interpreted as evidence for the unusal ability of amphiphilically equipped PPPs to segregate

lengthwise into polar and unpolar domains. Polymer 3 was synthesized successfully despite

sterically demanding, dendritic substituents (Scheme 4). It was reported that, because of the

enormous steric congestion at each repeat unit, they are exceptionally rigid proven by SFM

measurements[17] and attain a cylindrical shape in solution and when adsorbed on surfaces.[18]


7

O OO

O O

O

O

O

O O O O

O

O

O

O

O

O

O

O

O

OO O

O

O

O

O

O

O

n

O

O

OC12H25

O

O O

O

OO

O

O

O

OO

O

O

O

O

n

1 3

O

O

O

O

O OO

O O

OO

O

O O O O

O

O

O5

n

2

Scheme 4: Examples of three dendronized PPPs.

In the beginning, Rehahn and Ballauff described water soluble cationic PPP poly-electrolytes

with phenoxyether groups on the periphery.[19] Precursor polymer 6 which was readily available

via Pd-catalyzed polycondensation of 4 followed by ether cleavage was first reacted with TMSI

and finally a nucleophilic substitution reaction of 6 with triethyl amine or pyridine gave the

cationic polyelectrolyte 7, as shown in Scheme 5.

(CH2)6

(CH2)6

OPh

OPh

n

(CH2)6

(CH2)6

I

I

n

TMSI Pyridine

(CH2)6

(CH2)6

N

N

n

I-

I-

+

+

Br B(OH)2

(CH2)6

(CH2)6

OPh

OPh

Pd

4 5 6 7

Scheme 5: Synthesis of water soluble PPP polyelectrolyte 7 as described by Rehahn et al. [19]


8

Rehahn and co-workers[20] afterward selected TMEDA instead of a single amine to double the

charge density of the polyelectrolyte. Precursor polymer 6 was first reacted with a large excess of

TMEDA. This large excess was essential in order to suppress quaternization of both nitrogen

atoms. Polymer 9 was found to be exceptional because it carried four charges at every repeat unit

(Scheme 6).

+

(CH2)6

(CH2)6

I

I

n

(CH2)6

(CH2)6

N

N

n

TMEDA

CHCl3-MeCN

CH3

H3C CH2-CH2-N

CH3

H3C CH2-CH2-N

CH3

CH3 (CH2)6

(CH2)6

N

N

n

CH3

H3C CH2-CH2-N

CH3

H3C CH2-CH2-N

CH3

CH3

CH2CH3

CH2CH3

EtI

DMSO

6 8 9

I-

I-

I-

I-

I-

I-

+

+

+

+

+CH3

CH3

CH3

CH3

Scheme 6: Synthesis of water soluble cationic PPP polyelectrolyte 9 as described by Rehahn et

al. [20]

Wegner and co-workers[21, 22] reported the synthesis of PPPs with water soluble ethyleneoxy

side chains (polymers 10 and 11) as shown in Scheme 7. These polymers formed supramolecular

structures, in which the main chain was ordered in layered structures separated by an amorphous

matrix of side chains. The prepared polymers could possibly be used for ion transport and also as

matrix in ion batteries.[23]


9

Br Br

ORx

RxO

Br Br

ORy

RyO

+ +B BO

O O

O2

Na2CO3

Pd(PPh3)4THF/H2O

ORx

RxO

ORy

RyO

Br Br

OR

RO

+ B BO

O O

OOR

RO

Na2CO3

Pd(PPh3)4THF/H2O

n

n m

o

o

x

y

Rx =

Ry =

x = 2-6

y = 2-6

x y

10

11

Scheme 7: Synthesis of water soluble PPPs by Wegner et al.[21, 22]

1.3.2. Poly(meta-phenylene)s To our knowledge, only few reports describe the synthesis of poly(meta-phenylene)s (PMPs).

Most of the researchers obtained low molecular weight PMPs. Yamamoto et al.[24] reported

polymerization of m-dichlorobenzene using a transition metal catalyst. They claimed that the X-

ray diffraction pattern of poly(meta-phenylene) shows broad peaks which may be due to the

irregularities caused by the presence of both cis-trans and trans-trans configurations as shown in

Scheme 8.


10

Cl Cl

Mg

catalyst n

cis-trans

trans-trans

Scheme 8: Synthesis of poly(meta-phenylene)s by Yamamoto et al. [24]

Musfeldt et al.[25] reported a series of polyphenylenes which contain a specific number of

para-linked phenylenes separated either by meta-linkages or by severe steric distortions (see

Scheme 9). PMPs 12 and 13 were prepared by copolymerization to get biphenyl and p-terphenyl

repeat units, respectively, separated by meta-linkages. Homopolymerization of 3,3’-dichloro-p-

terphenyl yielded a polymer 14 which contains three para-linked phenylenes along the main

chain. The homopolymerization of 1,3-bis(4-chloro-phenyl)-5-phenylbenzene led to a polymer

(15) having a quaterphenyl repeat unit separated by meta-linkages. In the cases of

polyphenylenes 16 and 17, a pendant phenylene was attached to the meta-linked monomer in an

attempt to improve solubility. However, all polymerizations yielded toluene soluble as well as

toluene insoluble fractions. The molecular weights studied by both GPC and MALDI mass

spectrometry indicated that the toluene soluble fractions contained lower molecular weight

oligomers only. Typical GPC molecular weights determined against polystyrene standards ranged

from 1000-1500 g/mol.


11

n

n

n

n

n

n12 13 14

15 16 17

Scheme 9: Different para-linked phenylenes synthesized by Musfeldt et al. [25]

Reynolds and co-workers reported the preparation of alkoxy-functionalized PMPs[26] (see

Scheme 10). The monomer, 3,5-dichloro(dodecyloxy)benzene, was prepared via classical

Williamson ether synthesis. Polymerization was accomplished using a nickel-catalysed

homocoupling reaction.[27] They proposed a relatively easy access to the monomer and polymer

synthesis, however, the molecular weight determined (Mn = 9700 g/mol) indicates that only low

molar mass PMPs were obtained. Reynolds reported that, the material obtained was light

emitting.[26]

ClCl

OH

ClCl

OC12H25 OC12H25

C12H25Br

K2CO3

acetone

NiCl2

ZnDMF or DMAc

n

18

Scheme 10: Alkoxy substituted PMP synthesized by Reynolds et al.[26]

Ramakrishnan et al.[28] reported the synthesis of amphiphilic PMPs by oxidative coupling of

1,3-disubstituted benzene monomers using ferric chloride in nitrobenzene (Scheme 11). They

obtained relatively low molar mass PMPs. Despite this, the monomers shown in Scheme 11 were

polymerized into corresponding polymers having a bimodal distribution of molecular weights.

The polymer samples were fractionated in methanol from chloroform solution and the formation


12

of high molecular weight material was reported in low yields. High molecular weight fraction 1

(polymer 19, R = d) gave Mn = 140700 g/mol, with 35% of the total amount of polymer formed)

FeCl3

PhNO2

R = a) CH2COOCH3

b) CH2COOC8H17

c) C3H6COOEt

d) C10H20COOCH3

19

OR

OR

OR

OR

n

Scheme 11: Polymerization of 1,3-dialkoxy benzene derivatives by oxidative coupling

reaction.[28]

Yamamoto and co-workers reported another synthesis of PMPs, again obtaining only low

molecular weight polymers.[29] The reaction was a polycondensation of 1,4-substituted benzene

and 1,3-substituted benzene using Mg and nickel catalyst as shown in Scheme 12.

XX Xn mn

m

Mg

SnRX Xn mn

mSnR

X

+

+

X = halogensR = alkyl group n and m = repeating units

20

21

Ni

Ni

Scheme 12: Synthesis of PMPs, as described by Yamamoto et al. [29]

1.3.3. The Suzuki-Miyaura cross coupling reaction

Transition metal catalyzed cross-coupling reactions have brought a kind of “revolution” in

organic synthesis.[30] Many efficient and mild protocols for C-C bond formation following cross

coupling reactions were reported in the past. Amongst other cross-coupling reactions, e.g. the

Heck[31] or Stille reaction,[32] the Suzuki-Miyaura reaction is a superior coupling reaction in terms

of catalyst used and reaction conditions.[33] The Suzuki-Miyaura reaction is a palladium-catalysed


13

coupling of organic halides or triflates with organoboranes under basic conditions (Scheme 13). It

is a highly versatile method for the formation of C-C bonds.

XY

+ (HO)2BZ

Pd Y

Z

X = I, Br , Cl , OTf, ONf

Y = Ester, Aldehyde, Ketone, Amine, Ether, ...........

Z = CH3, C2H5, Phenyl........

Scheme 13: General reaction scheme for the Suzuki-Miyaura reaction.[31]

The main advantage of this reaction is its applications to various functional groups such as

esters, carboxylic acids, aldehydes, ketones, protected amines and alcohols as well as ethers

(Scheme 13). Other advantages are i) high regio- and stereo-selectivity, ii) easy separation of

inorganic boron compounds, iii) easy use of the reaction both in aqueous as well as

heterogeneous reaction conditions and most importantly, iv) high yields. Because of its high

yields the Suzuki-Miyaura reaction could even be introduced as a polycondensation method to

macromolecular chemistry.

As shown in Scheme 14, the mechanistic pathway of the Suzuki-Miyaura cross-coupling

reaction involves three steps viz oxidative addition, transmetalation and reductive elimination to

afford the coupling partner. The Pd(0) complex, formed by dissociation of ligands of the catalyst

precursor, gets inserted between the R1-X (aryl halide) bond. The oxidative addition of organic

halides to a catalytically active Pd (0) species affords a stable trans-R1-Pd(II)-X complex (II).

This step is often the rate-determining step in a general catalytic cycle. For transmetalation,

Suzuki et al.[34] proposed one intermediate step before reductive elimination whereas Canary et

al.[35] proposed two such steps as shown in Scheme 14. Suzuki et al.[34] proposed that R1-Pd(II)-X

complex (II) reacts with aryl boronic acids or esters and results into biaryl Pd intermediate IV

(transmetalation step). The reductive elimination of the biaryl product (IV) regenerates the

catalytically active Pd (0) species to continue the catalytic cycle. Canary et al.[35] proposed that

transmetalation of B→Pd occurs to form a trans-diarylpalladium species (III); isomerization of

the trans isomer into the cis isomer gives IV. Although the two steps of oxidative addition and


14

reductive elimination are reasonably well understood, less is known about the transmetalation

step. Pd(0) L4

Pd(0) L2

+ 2L -2L R1-X

R2-B(OH)2

B(OH)3 + HX

R2R1Oxidative addition

TransmetalationTrans-Cis isomerization

Reductive elimination

I

II

III

IV

PdX

R1 LL

PdR2

R1 LL

PdL

R1 LR2 +2

+2

+2

Transmetalation

Suzuki pathway

Canary pathway

R2-B(OH)2

XB(OH)2

XB(OH)2

Scheme 14: Postulated reaction mechanisms of the SCC reaction by Suzuki et al.[34] and Canary

et al.[35] (X = halogens, OTf or ONf and L = ligand).

Suzuki et al.[34] and Canary et al.[35] proposed different reaction mechanisms for the SCC

reaction, based on experimental observations only. In an earlier work, Suzuki et al.[34] proposed a

reaction cycle with the formation of intermediate IV before reductive elimination (see Scheme

14). However, Canary et al.[35] demonstrated by electro spray ionization mass spectrometry (ESI-

MS) that III is a plausible intermediate: The Suzuki cross coupling reaction of pyridyl bromide

with three structurally similar phenyl boronic acids was examined (Scheme 15).


15

NBr + (HO)2B

R1

R2

R1

R2N

Pd

R1= R2 = HR1= H, R2 = CH3R1= R2 = CH3

R1=R2 = HR1= H, R2 = CH3R1= R2 = CH3

Scheme 15: The Suzuki reaction studied by Canary et al.[33] The reaction mixture was analysed

by ESI-MS.

From these investigations Canary discovered that the species [(PyrH)Pd(PPh3)2Br]+ and

[(PyrH)(R1R2C6H3)Pd(PPh3)2]+ formed. In some cases, species of similar molecular weight were

not resolved due to the large number of naturally abundant palladium isotopes and the use of a

relatively low resolution spectrometer. The reaction mixture contained the two key intermediate

II and IV, as shown in the catalytic cycle (Scheme 14). Both mechanisms do not contradict

themselves necessarily, since the substitution of the halide with another anion depends perhaps

on the selected reaction conditions and the substrates used for the coupling reaction.

The palladium catalyzed Suzuki cross coupling reaction[36-38] carried out under basic

conditions is frequently considered as the method of choice for the formation of C-C bonds.

Soderquist’s et al.[39] mechanism for the SCC coupling reaction is shown in Scheme 16 in detail.

This mechanism differs from the suggested catalytic cycle of the normal Suzuki reaction

particularly if a base is included.[40] The new features of the catalytic cycle are illustrated in

Scheme 16 and discussed in the following.

In solution the catalyst [Pd(PPh3)4] splits off into two phosphine ligands and the Pd(0) species

A which reacts with the carbon electrophile B via oxidative addition to form Pd(II) complex C.

This step is often the rate-limiting step in a general catalytic cycle at ambient temperature. The

organoboranes D are present principally as their hydroxyborate complexes E. The reaction of E

with C is rapid, probably displacing the halide and forming a hydroxo μ2-bridged intermediate F

that facilitates the alkyl B→Pd transmetalation with retention of configuration through a four-

centered transition state G. Intermediate G would also be expected to be of lower energy than

that of a related species derived from more oxygenated organoboranes such as E.

Transmetalation under retention of the configuration to the α-CH2-group of the alkyl substituent

gives cis complex H.[41, 42] Product J in the reaction mixture reacts with a second equivalent of


16

hydroxyl ions to form K. The palladium complex H reacts rapidly under reductive elimination to

give coupling product I with simultaneous regeneration of the active species A. Pd(0) L4

Pd(0) L2

+ 2L -2L

Ar-X

Oxidativeaddition

PdX

Ar

L

L

B

HH

R

B

HH

R

OH-

HO

B

HH

R

O

PdAr

L

L

+2

+2

Pd

B

O

HR

H

H

LAr

L

PdL

Ar L

+2

X

Transmetalation

BHO

OH-

BHO

HO

Ar CH2R

Reductiveelimination

AB

C

D

E

F

G

H

I

J

K

HR H

H

Scheme 16: Modified Suzuki-Miyaura catalytic cycle as described by Soderquist et al.[39] (X =

halogens, OTf or ONf and L = ligand).

The Suzuki-Miyaura cross coupling reaction generally gives products with excellent yields.

Suzuki couplings are used not only in research laboratories[43-45] but also on industrial scales.[46,

47] The biaryl motif is found in a range of pharmaceuticals, herbicides and natural products as

well as in conducting polymers and liquid crystalline materials.[48-50]

1.3.4. Suzuki polycondensation

Suzuki polycondensation (SPC) has been developed into an important tool for the synthesis of

polyarylenes and related polymers.[51] It is a Pd-catalyzed step growth polymerization of aromatic

dihalides and arylboronic acid esters. This polycondensation reaction can be carried out in two

different ways as shown in Scheme 17. In the AB-type approach, bromide or iodide and the

boronic acid or boronic esters groups are present on the same monomer (Scheme 17a) whereas in


17

the AA/BB-type approach, bromide or iodide and the boronic acid or boronic esters groups are

present on different monomers (Scheme 17b). Both approaches have been successfully applied

for the synthesis of polyarylenes. It is now one of the few established step-growth polymerization

reactions that proceed with formation of carbon-carbon bonds. The mechanism of this reaction is

supposed to follow the same path developed for the Suzuki-cross coupling reaction.

(a)

(b)

Scheme 17: Graphical representation of SPC applied to amphiphilically substituted AB

monomers (a) or AA/BB monomers (b). The circle represents an aromatic unit, typically benzene

derivatives. (red: hydrophobic; blue: hydrophilic). X = Br or I.

Amongst these two approaches, the work carried out so far mainly focused on the AA/BB

type Suzuki-polycondensation. There is a simple synthetic reason why this is so. Normally it is

easier to synthesize aromatic monomers with two identical substituents in opposite positions than

monomers with different substituents. An additional factor is that once an aromatic dibromide is

obtained, its conversion into the corresponding diboronic acid or ester can often be achieved in

one step. The price, which has to be paid for the AA/BB approach, however, is the necessity to

apply the AA and BB monomers in strictly equal molar amounts. This requirement sounds almost

trivial on paper. In reality, however, it may turn into a real experimental challenge. Purities,


18

methods of how to completely transfer monomers into the polymerization vessel and losses of a

part of the functional groups during polymerization become important and all of a sudden even

critical aspects, when the molar mass difference between two monomers is very large.[52]

A wide range of Pd (0) catalysts or precursors can be used for the cross coupling reaction, for

example, Pd(PPh3)4 is most commonly used as catalyst precursor. Ortho- and para-tolyl ligands

also proved successful in SPC. The best results of polycondensation are obtained when the Pd

complexes are freshly prepared and used immediately after recrystallization. Even if it is kept in a

Teflon-sealed tube in a high quality glove box (< 1 ppm oxygen), the catalyst precursor still

“ages”. This inevitably leads to reduction of molar mass after a few days of storage. It is therefore

essential to only use freshly prepared material if high molar mass polymers are to be achieved.

The polycondensation reaction can be carried out with various bases and solvent systems. This

reaction requires the presence of base such as Na2CO3, K2CO3, KF, Cs2CO3 or NaHCO3 and is

usually carried out in a two-phase solvent system such as toluene/water or THF/water. Other

solvent systems can also be applied, e.g DMF for SPC of both water-soluble monomers and

catalyst precursors.

In step-growth polymerization, many difficulties are frequently met in practice when high

molar mass material is concerned. Carothers, the pioneer of step-growth reactions, proposed a

simple equation.[53] Considering a polymerization in which two bifunctional monomers AA and

BB are present, the number average degree of polymerization nX with respect to the molar

amount ratio of two monomers r = [AA]/[BB], and the extent of conversion p can be expressed

as

nX = (1 + r)/(1 + r - 2rp) (1.1)

If the two reactants are present in stoichiometric amounts, i.e., r = 1, eq 1.1 reduces to

nX = 1/(1-p) (1.2)

This relationship explains why the extent of reaction must exceed 99% in order to achieve a

high molecular weight. Eq. 1.2 is very useful, because it applies to the initial system that consists

of both AB-type monomer and AA/BB type monomers. Further, if polymerization is taken to

100% conversion (p =1), i.e., until all functional groups of type A or B have reacted, Eq. 1.1

reduces to

nX = (1+r)/(1-r) (1.3)


19

This equation clearly shows how the molecular weight of the polymer obtained is affected by

the stoichiometric imbalance of the initial mixture. It is seen in Figure 2 that high molar mass

polymers can be obtained only if the initial concentrations of the A and B type groups are very

close to a 1:1 stoichiometry and the conversion is sufficiently high.

Figure 2: Effect of r = [AA] /[BB] and conversion p for a polycondensation of AA and BB

monomers.[53]

Chapter 2 Synthesis and characterization of amphiphilically equipped PPPs

20

2. Synthesis and Characterization of Amphiphilically Equipped

Poly(para-phenylene)s (PPPs) 2.1. Amphiphilic substituents Amphiphilies are molecules that are composed by two moieties: a hydrophobic and a

hydrophilic part. In view of the important development for both supramolecular chemistry and

nanotechnology, a new rigid-rod amphiphile with an unusual amphiphilic structure was designed

and synthesized. The general structure is shown in Figure 3. The primary structure consists of a

rigid PPP backbone substituted with hydrophobic and hydrophilic chains, which together renders

the polymer amphiphilic. Each repeating unit resembles an amphiphile in itself. These repeating

units are tied together covalently in a linear fashion. The polar and non-polar parts have the

potential to segregate lengthwise along the backbone and not perpendicular to it. Because of the

rigid backbone this class of polymeric amphiphiles may give rise to novel and interesting

supramolecular aggregates. The hydrophobic and hydrophilic substituents could be introduced on

the same monomer or on different monomers. Synthetically it is easy to synthesize the

amphiphilic monomer first and then convert amphiphilicity into the corresponding polymer.

Figure 3: Amphiphilic PPP with a novel structural motif (aromatic units represent the rigid rod

backbone, red: hydrophobic substituents; blue: hydrophilic substituents).

The hydrophobic substituents of the target amphiphilic PPP should have a characteristic

alkane backbone, which is composed of primarily carbon and hydrogen atoms. The simplest

hydrophobic substituents are alkyl chains. These are characterized by their chemical inertness and

they are easy to introduce by Kumada coupling[54] or Suzuki-Miyaura cross coupling.[55]


21

Alternatively also the likewise nonpolar alkyloxy substituted chain could be attached by using

Williamson’s etherification. An additional advantage of terminal monofunctional alkyl chains is

that, they are commercially available in various lengths. The variation of the alkyl chain length

affects the later aggregation behavior.[56, 57]

Hydrophilic substituents are those with electronegative groups in their structure. So far, water

soluble oligoethylenglycol (OEG) chains were most frequently used as hydrophilic

substituents.[21, 22] Advantages of the OEG chains are their good solubilities in various organic

solvents and the commercial availability with different OEG chain lengths. Besides OEG chains,

sulfonates,[58] quaternary ammonium salts[20] and carboxylates[59] were reported as a hydrophilic

substituents by several groups.

2.2. PPPs with alkyl and oligo(ethylene oxy) (OEO) chains 2.2.1. Synthesis of amphiphilic dibromo monomer 30

The synthesis of monoalkylated building block 24 starts from benzene-1,4-diol 22.

Electrophilic addition of bromine to diol 22 gave 2,5-dibromobenzene-1,4-diol 23, which carries

appropriate functions for both chain attachment and SPC. Compound 23 was prepared on

multigram scale following a reported protocol.[60] Monoalkylation of diol 23 was carried out in a

statistical Williamson’s etherification reaction with NaOH in dry ethanol to give 24 in 60% yield

as shown in Scheme 18. The doubly alkylated byproduct was removed by filtration.

Desymmetrization of 23 was reported using butanone as solvent in low yield (33%) of

monoalkylated building block.[61]

BrBr

OH

HO

OH

HO

24

Br2 C12H25Br

dry ethanol

BrBr

OC12H25

HONaOHacetic acid

2322

Scheme 18: Synthesis of monoalkylated hydroquinone derivative 24.

A symmetrical branched oligoethyleneoxy (OEO) chain was prepared as hydrophilic sub-


22

stituent in two steps according to a reported procedure.[21] First, the ring opening of epichloro-

hydrin (26) was initiated with the sodium salt of triethylene glycol monomethyl ether (27) -

prepared from 25 - and gave the corresponding branched secondary alcohol 28. The symmetrical

alcohol 28 was activated as mesylate using methane sulfonyl chloride and triethylamine in

CH2Cl2 to yield 29, as shown in Scheme 19.

OO

OHO

Na

OO

O-O+O

Cl

O

OO

O

O

OO

OHO2 Na+

25

26

27 28

O

OO

O

O

OO

OO

29

SH3CO

O

CH3SO2Cltr iethylamineCH2Cl297%

Scheme 19: Synthesis of the symmetrical OEG alcohol 28 and its corresponding mesylate 29.

The activated mesylate 29 was hooked onto the monoalkylated building block 24 with K2CO3

in dry acetonitrile (yield 65%) which afforded amphiphilic dibromo monomer 30 as shown in

Scheme 20.

24

BrBr

OC12H25

HO

BrBr

OC12H25

O

OO

OO

OO

OO

+ 29

30

K2CO3

acetonitrile65%

Scheme 20: Synthesis of amphiphilic dibromo monomer 30.


23

2.2.2. Synthesis of amphiphilic diiodo monomer 36

There were only few reports in the literature for the use of diiodo monomers in SPC.[62]

Usually, these monomers do not yield higher molecular weight products as compared to their

dibromo analogs.[62c] In order to compare the reactivity of the dibromo and diiodo monomers

towards SPC, the amphiphilic monomer 36 was synthesized. Its synthesis begins with the

reaction of 1,4 dimethoxybenzene 32 with iodine to afford diiodide 33. Demethylation of 33 was

then achieved by means of boron tribromide.[63] Monoalkylation of the resulting 2,5-

diiodobenzene-1,4-diol 34 was accomplished in a statistical Williamson’s etherification reaction

with NaOH in dry ethanol to give 35 in 56% yield as shown in Scheme 21. The undesired doubly

alkylated byproduct was removed by filtration. The activated mesylate 29 was attached onto the

monoalkylated building block 35 with K2CO3 in dry acetonitrile to give amphiphilic diiodo

monomer 36.

35

II

OC12H25

HO

II

OC12H25

O

OO

OO

OO

OO

+ 29

36

K2CO3

acetonitrile65%

32

OCH3

H3CO

KIO3

84 %

33

II

OCH3

H3COI2

H2SO4

BBr3

76 %

34

II

OH

HOCH2Cl2

56 %

C12H25Br

dry ethanol

Scheme 21: Synthesis of amphiphilic diiodo monomer 36.

Purification of monomers in Suzuki polycondensation is a very important task in order to

achieve a 1:1 stoichiometry (see 1.3.4). The purity of the monomers was determined by high

resolution 700 MHz 1H NMR spectroscopy and micro analysis. Figure 4 shows the 700 MHz 1H

NMR spectrum of monomer 36. The inset shows the aromatic region. The small peak at chemical


24

shift δ = 2.5 ppm was due to solvent impurity. This solvent impurity remains even after drying

the substance under high vacuum for several hours. As shown in Figure 4, proton b showed

carbon satellite signals at δ = 6.8 and 7.1 ppm, however the signal at δ = 7.0 ppm was from the

starting material. The small peak at δ = 7.0 ppm was compared with the carbon satellite signals of

proton b. From this comparison and considering natural abundance of 13C of 1%, the purity of

monomer 36 was determined to be beyond 99.5%.

Figure 4: 700 MHz 1H NMR spectrum of amphiphilic monomer 36 in CDCl3 at 20 °C.

2.2.3. Synthesis of amphiphilic monomer with a linear OEO chain

The PEG chain 38 (see Scheme 22) required for the synthesis of monomer 39 was prepared by

anionic polymerization, resulting in a polymer with a polydispersity index (PDI) of 1.1. Although

the anionic polymerization does not supply molecularly uniform products, the molecular weight

distribution is quite low as compared with other polymerization processes. The polydispersity of

the side chains, however, brings a new problem with itself: one transfers naturally the

polydispersity of the chains during monomer preparation. This means that the monomers will not


25

be uniform. Long PEG chains are advantageous because of their water solubility, while for

shorter chains the relationship between hydrophobic to hydrophilic portion is decisive. In the

present work, polyethylenglycol monomethylether 750 was used, which has an average molecular

mass of 750 g/mol, i.e. 17-18 repeating units on average (18 repeat units were confirmed by

MALDI TOF mass spectrometry). The one-sided methyl protecting group permits selective

chemistry at the hydroxyl functional group. The linear OEO chain 38 required for monomer 39

was commercially available and attached to 24 under Mitsunobu reaction conditions

(PPh3/DIAD) to give amphiphilic dibromo monomer 39 as shown in Scheme 22. OC12H25

OBr

Br

O1824 39

+

38

PPh3

DIAD60%

OC12H25

OHBr

Br

HOO

O 17

Scheme 22: Synthesis of amphiphilic monomer 39.

In this step, the Mitsunobu reaction[64] was used to couple a phenol and an alcohol to obtain an

alkyl aryl ether. The literature proposes that the etherification reaction of an alcohol with

PPh3/DIAD takes place in four steps as shown in Scheme 23: (I) reaction of Ph3P with DIAD in

the presence of the acidic component to form a salt wherein a phosphorus-nitrogen bond is

formed; (II) reaction of the DIAD-Ph3P adduct with the alcohol to form an activated

oxyphosphonium ion intermediate; and (III) displacement via SN2 process to form the desired

ether (IV) and triphenylphosphine oxide (TPPO). The driving force for this reaction is the

formation of thermodynamically stable TPPO. The reaction is advantageous due to its high

functional groups compatibility and mild reaction conditions.


26

R1ON N

OR1O

O+ PPh3 R1O

N NOR1

O

OPPh3

R2OH

R1ON N

OR1O

PPh3O

H

R2O

R3OH

R1ON N

OR1O

OH

H

PPh3

OR2

+P OPh

PhPh

+

OR2

R3

I

II

III

IV

R3O

Scheme 23: Mechanism of the Mitsunobu-reaction (R1: -CH(CH3)2; R2: Azides Phenol; R3:

PEG).[64]

2.2.4. Synthesis of boronic ester

The free boronic acid 41 (see Scheme 24) was prepared from bromobenzene using the

Grignard reaction. It is well known that phenylboronic acid 41 self condenses simply by heating

to form cyclic triphenyl boroxin 42[65] as shown in Scheme 24. Furthermore, it is not easy to

remove traces of water from free boronic acid which represents a problem in achieving a correct

stoichiometry for the planned polycondensation reaction (see 1.3.4). It was therefore decided to

use a diboronic acid and to convert it into the corresponding ester by cyclization reaction with

1,3-propane-diol using a Dean-Stark water trap.


27

OB

OBO

B

B(OH)2-3 H2O

41 42

Scheme 24: Trimerization of phenylboronic acid 41.

Following this consideration, two symmetrical diboronic ester monomers were prepared and

the purity of the monomers was confirmed by high resolution 1H NMR spectroscopy and correct

values from micro-analysis.

2.2.4.1. Synthesis of benzene diboronic acid ester 45

Compound 45 was synthesized by the dehydration reaction of 1,4-phenylenediboronic acid 43

and 1,3-propane-diol 44 in toluene.[66]

B(OH)2(HO)2B + HO OH BBO

O O

O

43 44 45

toluene

91%

Scheme 25: Synthesis of benzene diboronic acid ester 45.

Boronic ester 45 was purified by two times recrystallization in diethyl ether and the purity was

determined by recording a 700 MHz 1H NMR spectrum in CDCl3, as shown in Figure 5. The

inset shows corresponding amplified signals. In order to estimate the purity degree of monomer

45, the carbon satellite signals were integrated from the proton b (4.1 and 4.3 ppm). The signals

shown by red arrows at chemical shift δ = 1.2 ppm and δ = 3.5 ppm are from the solvent (diethyl

ether) present from recrystalization. As shown in Figure 5, the integration of carbon satellite of

proton b (1.0) was compared with -OCH2 from diethyl ether (0.32). From this comparison, the

purity of compound 45 was determined to be beyond 99.5% (This may be so in regard to Et2O

but cannot be generalized for all possible impurities).


28

Figure 5: 700 MHz 1H NMR spectrum of benzene diboronic acid ester 45 in CDCl3 at 20 °C.

The arrows indicate signals that arise from the solvent (diethyl ether).

2.2.4.2. Synthesis of the diboronic acid ester 48

The double lithiation of 46 was accomplished with 2.2 equivalents BuLi in hexane. The

boronic acid 47 was synthesized by addition of 3 equivalents trimethyl borate at – 78 °C. The

diboronic acid was esterified with 1,3-propane-diol 44 in CH2Cl2 as shown in Scheme 26. The

diboronic ester 48 was recrystallized from ethyl acetate/hexane and then THF.

n-BuLi

B(OCH3)3

BrBrn-BuLi

B(OCH3)3

BBHO

HO OH

OH

HO OH

CH2Cl2BB

O

O O

O

46 47 48

Scheme 26: Synthesis of benzene diboronic acid ester 48.


29


The Suzuki cross coupling (SCC) reaction was introduced as a Suzuki polycondensation

(SPC) method to macromolecular chemistry. Mechanistically SPC is believed to follow the same

path postulated for the SCC reaction.[33] It is a step growth polymerization of aromatic dihalides

and boronic acids (or esters) with Pd(0) complexes as catalyst precursors. The polymerization

conditions for monomers bearing alkoxy[67-68] and oxyethylene side chains[69] were investigated in

detail. In the beginning of this work, only a few researchers described the use of an additive in

the SCC reaction. Badone and co-workers[70] reported that the addition of one equivalent of

tetrabutyl ammonium bromide (TBAB) to the reaction mixture greatly accelerates the Suzuki-

Miyaura reaction. Thereafter, Leadbeater et al.[71] proposed that, the role of ammonium salts in

the SCC reaction is thought to be, two fold: a) the ammonium salts facilitate the solvation of

organic substrates in the solvent medium, and b) ammonium salts are thought to enhance the rate

of the coupling reaction by activating boronic acid. Therefore, some trial SPC reactions were

carried out with the addition of TBAB during optimization experiments.

Polymers 31, 37 and 40 were chosen for a series of optimization experiments. Several

polymerization reactions were carried out by changing catalyst precursors, base and addition of

TBAB as an additive. A few parallel SPC reactions were performed with and without addition of

TBAB in order to confirm the effect on the molecular weights. Polymers 31, 37 and 40 were

prepared by using the AA-type monomers 30, 36 and 39 respectively and combining them with

the BB-type monomer benzene diboronic acid ester 45[66] as shown in Scheme 27.

The reaction was carried out in a two-phase solvent system (THF/H2O) and NaHCO3 as

base[72-75] using freshly prepared Pd(PPh3)4[76] or Pd[P(p-tolyl)3]3

[77] as catalyst precursors and

TBAB as an additive. The catalyst precursors were used immediately after recrystallization. To

meet the required exact 1:1 stoichiometry of monomers, a series of polymerization experiments

were carried out. For each entry, about 500 mg of dihalo monomers were used. Experimentally, it

is not easy to avoid any loss of material while transferring the weighed monomers into the

reaction vessels. The slight loss may cause strong deviation from the intrinsically obtainable

molecular weight if the molar mass difference between two monomers is very large. Therefore a

series of SPC reactions were carried out between the two monomers in order to achieve at least in

a few cases a precise 1:1 stoichiometry.


30

OC12H25

Y

XX

OC12H25

Y

BBO

OO

O+

Pd

45

nNaHCO3

THFwater

30 : X = Br, Y = R

36 : X = I, Y = R

39 : X = Br, Y =18

31 : Y = R

37 : Y = R

40 : Y =

OO

OO

OO

OO

O

OO

CH3

18O

OCH3

R =

~ 90%

Scheme 27: Synthesis of amphiphilic polymers 31, 37 and 40.

Table 1: Conditions and average molecular weights of polymers 31, 37 and 40 obtaineda.

Entry

Monomer

TBAB

Catalyst

precursors

Polymer

Mn

[kg/

mol]

Pn Mw

[kg/

mol]

Pw

PDb

equiv Nr Yield

[%]

1 30 - c 31 93 8.7 12 10.2 14 1.2

2 30 1.0 d 31 87 29.5 41 51.5 72 1.7

3 30 - d 31 92 23.6 33 47.5 66 2.0

4 30 - d 31 81 18.9 26 42.3 59 2.2

5 30 1.0 d 31 94 24.6 34 44.4 62 1.8

6 30 1.0 d 31 91 25.3 35 47.4 66 1.8

7 30 - d 31 93 22.8 32 39.9 56 1.7

8 36 - c 37 86 16.8 23 29.2 41 1.7

9 36 - d 37 92 18.9 26 33.5 47 1.8

10 36 - d 37 96 19.5 27 76.1 106 3.9

11 39 - d 40 91 32.2 24 65.9 50 2.1

12 39 1.0 d 40 87 26.7 20 58.2 44 2.2

13 39 - d 40 96 26.0 20 55.8 40 2.2 a. The measurements were carried out by GPC with THF as eluent and PS as standard.

b. PD = Mw/Mn


31

c. Freshly prepared Pd(PPh3)4

d. Freshly prepared Pd[P(p-tolyl)3]3

All polymers are completely soluble in THF, CH2Cl2, CHCl3 and partially soluble in toluene.

All polymers gave perfect or near-perfect results from combustion analysis. The average

molecular weights were determined by GPC calibrated with polystyrene standards. The following

five results can be extracted from Table 1: First, polymer yields are high throughout and usually

beyond 90%. Second, the catalyst precursor Pd(PPh3)4 used to make polymers 31 and 37 (entries

1 and 8) is inferior to Pd[P(p-tolyl)3]3. Both catalyst precursors were freshly prepared and used

immediately for SPC reaction, though Pd[P(p-tolyl)3]3 gives higher molecular weight polymers as

compared to Pd(PPh3)4. The first was, therefore, used throughout. Third, polymers 37 and 40 are

the ones with the highest molecular weights, the apparent weight-average ( wM ) being ca. 46 and

60 kg/mol, respectively. Fourth, the experiment of entry 10 in Table 1 shows the highest wM

value of the entire table ( wM ca. 76 kg/mol), which indicates that the diiodo monomer 36 is

superior in comparison with the same dibromo monomer 30. However, the results of entries 8

and 9 for the same diiodo monomer show that it is not trivial to experimentally meet the correct

stoichiometry. The polymerization behavior of monomers 30 and 36 were compared with one

another in order to contribute to the discussion of the still open question whether or not diiodo

monomers are superior to dibromo ones in SPC.[78] Five, two parallel experiments of SPC were

performed for a direct comparison of obtainable molecular weights, one with TBAB (entry 12,

Table 1) and one without TBAB (entry 13, Table 1). Addition of 1 equivalent amount of TBAB

doesn’t show a significant molecular weight difference, therefore all SPC reactions in the present

work were carried out using standard SPC conditions without addition of TBAB.

Figure 6 shows the 13C NMR spectrum of polymer 31 prepared from the dibromo monomer 30

(entry 2, Table 1) with an inset of the spectrum of the same polymer prepared from diiodo

monomer 36 (entry 2, Table 1) to prove the formation of identical products.


32

Figure 6: 126 MHz 13C NMR spectrum of polymer 31 (entry 2, Table 1) in CDCl3. The inset

shows the aromatic region of the same polymer prepared from the diiodomonomer 36 (entry 10,

Table 1).

Figure 7: 500 MHz 1H NMR spectrum of polymer 37 (entry 10, Table 1) in CD2Cl2 at 20 °C.


33

Figure 7 shows the 500 MHz 1H NMR spectrum of polymer 37 (entry 10). All signals are

broad. All peaks can be correlated with the chemical shift of 37, i.e. the NMR spectrum supports

the molecular constitution of polymer 37. Therefore, a structurally defined polymer was obtained.

The small peak at chemical shift δ = 1.6 ppm was due to solvent impurities.

2.2.6. Determination of Molecular Weights

Figure 8: Top: SEC chromatograms (eluent: NMP + 0.5 wt.-% LiBr, 70 °C) of polymer 40 (entry

11 in Table 1) and 37 (entry 10 in Table 1). Bottom: mass distributions W (log M) of 40 (black

line) and 37 (gray line) as determined by universal calibration.


34

For the determination of molecular weights of the polymer samples, SEC analyses were

initially performed in THF as the eluent on the basis of a calibration with PS standards. All

samples exhibited monomodal GPC curves with the polydispersity index ( wM / nM ) being in the

range of 1.4–2.2 (Table 1) for almost all products. It is known from the work of Köhler et al.[79]

that SEC may overestimate the molecular weights of rigid-rod polymers namely, PPPs with bulky

sulfonate ester and dodecyl chains when a PS calibration curve is used. In order to see if this is

true for our samples, we selected the highest molecular weight polymers 37 (entry 10, Table 1)

and 40 (entry 11, Table 1) and analyzed them by SEC with online UV and differential viscosity

detection and universal calibration[80] (Figure 8 and Table 2).

N-Methylpyrrolidone (NMP + 0.5 wt.-% LiBr) was chosen as the eluent and a polyester gel as

the stationary phase (column temperature: 70 °C). Under these conditions, polymers 37 and 40

seemingly neither formed aggregates nor were adsorbed onto the column material. For samples

37 and 40 calibration with PS yielded wM values of 48 and 64 kg/mol, respectively, which are in

good agreement with the values obtained in THF (see Table 1). Universal calibration, on the

other hand, provided higher values, i.e., wM = 76 (polymer 37) and 88 kg/mol (polymer 40).

Accordingly, the values given in Table 1 may be considered as underestimates of the true

molecular weights.

Table 2: Molecular characteristics of polymers 37 and 40 as determined by SEC (eluent: NMP +

0.5 wt.-% LiBr, 70 °C) with standard and universal calibration.

Entry in

Table 1

Polymer

Use of

standard calibration

Use of

universal calibration

nM

[kg/mol]

wM

[kg/mol] wM / nM

nM

[kg/mol]

wM

[kg/mol] wM / nM

10 37 29.1 48.4 1.7 41.2 88.7 2.2

11 40 30.3 64.2 2.1 49.9 76.4 1.5


35

2.2.7. Synthesis of amphiphilic monomers 51 and 55 and their poly(para-

phenylene)s 52 and 56 2.2.7.1. Synthesis of amphiphilic monomer 51

1-(Bromomethyl)-4-dodecylbenzene 49 was prepared by bromination of (4-dodecylphenyl)

methanol using phosphorus tribromide.[81] The bromination of 1-(bromomethyl)-4-dodecyl-

benzene 49 was first attempted in CH2Cl2 at 0 °C and afterwards at 40 °C. Under these conditions

the desired product was obtained in only 45-50% yield. In order to affect polarizability of Br2,

different solvents were used for the reaction. The reaction was explored in acetic acid, hexane

and carbon tetrachloride. The variation of the solvent did not result in a significant difference.

The iodine-catalyzed method was accomplished with bromine in dichloromethane at 0 °C to

obtain 50 in 98% yield. Subsequent reaction of tribromide 50 with the branched OEO chain 28 in

the presence of KOtBu afforded amphiphilic monomer 51 in 84% yield as shown in Scheme 28. C12H25

Br

C12H25

Br

Br Br

C12H25

O

Br Br

OO

OO

OO

OO

49 50 51

Br2

CH2Cl298 %

28KOtBu

THF78 %

Scheme 28: Synthesis of amphiphilic monomer 51.

2.2.7.2. Synthesis of chiral amphiphilic monomer 55

After conversion of 2-(S)-methylbutanol into the corresponding chiral alkyl bromide 53, 2,5-

dibromohydroquinone was etherified with the chiral alkyl bromide 53 using the classical

Williamson’s etherification reaction. Monoalkylated 2,5-dibromohydroquinone product 54 was

isolated in 63% yield. The side product formed by double alkylation was removed by filtration.

The activated mesylate 29 was attached onto the monoalkylated building block 54 with K2CO3 in

dry acetonitrile and gave 55 in 81% yield as shown in Scheme 29.


36

BrBr

O

HO

BrBr

OH

HO

*

O

O

O

Br Br

O

OO

OO

OO

*

Br

*

+

23 53 54 55

NaOH

dry ethanol63 %

K2CO3

acetonitr ile81 %

29

Scheme 29: Synthesis of amphiphilic monomer 55 with a chiral hydrophobic chain.

2.2.7.3. Synthesis of polymers 52 and 56

Polymer 52 and 56 were obtained from SPC of monomers 51 and 55 respectively in THF/H2O

using freshly prepared Pd[P(p-tolyl)3]3 as catalyst precursor and NaHCO3 as base (Scheme 30). A

series of optimization experiments was carried out according to the synthetic procedure described

in Chapter 2.2.5. The mole ratio between 51 and 45 and between 55 and 45 was slightly varied in

order to achieve a 1:1 stoichiometry and thus to obtain hopefully high molecular weight

materials. The results of the different polycondensation reactions are summarized in Table 3.

X

Y

BrBr

X

Y

BBO

OO

O+

Pd

45

n

NaHCO3

THFwater

55 : X =

OO

OO

OO

OO

O

OO

OO

OO

OO

O

O

*

, Y = R2

51 : X, C12H25 , Y = R1

56 : X = O

*

52 : X, C12H25 ,

, Y = R2

Y = R1

R1 =

R2 =

~ 93%

Scheme 30: Synthesis of amphiphilic polymers 52 and 56.


37

The polymers were characterized by their highly resolved, high-field 1H and 13C NMR spectra

as well as by the data from combustion analysis which matched calculated values (see

Experimental Section). Figure 9 shows one representative 500 MHz 1H NMR spectrum of

polymer 56 (entry 7, Table 3). All peaks support the molecular constitution of the product,

indicating that a structurally defined polymer was obtained. The small peak at δ = 1.61 ppm

originates from a solvent impurity.

Figure 9: 500 MHz 1H NMR spectrum of polymer 56 in CD2Cl2 at 20 °C. The signals labeled

with an asterix (*) arise from the solvent.

Both polymers are completely soluble in chloroform, CH2Cl2, THF and partially soluble in

toluene. The average molecular weights were determined by GPC against polystyrene standards.

The highest degree of polymerization for polymer 52 (entry 1, Table 3) was Pn = 25 (Mn = 18.3

kg/mol), Pw= 70 (Mw = 70 kg/mol) and for polymer 56 (entry 5, Table 3), Pn = 68 (Mn = 42.6

kg/mol), Pw= 166 (Mw = 103.4 kg/mol). All polymers prepared show monomodular GPC curves

with a polydispersity index usually in the range of 1.2–3.7. A typical monomodular GPC curve of

polymer 52 (entry 1, Table 3) was shown in Figure 10. Two conclusions can be drawn from

Table 3: (a) high molecular weight materials can be obtained by SPC (entries 1 and 2 for polymer

52 and entries 5, 6, 7 and 11 for polymer 56); (b) polymer yields are high throughout and usually

beyond 90%. It should be mentioned that most of the polymers prepared form transparent films


38

with high mechanical strength, which is an independent indication of the materials high molar

mass. The films were obtained by a simple solution casting technique.

Figure 10: Monomodular GPC curve of polymer 52 (entry 1, Table 3).

Table 3: Conditions (catalyst precursor: Pd[P(p-tolyl)3]3) and average molecular weights of

polymer 52 and polymer 56 prepared.a

Entry Monomer Polymer

Yield

[%]

Mn

[kg/mol]

Pn

Mw

[kg/mol]

Pw

PDb

1 51 52 91 18.3 25 50.4 70 1.2

2 51 52 93 14.0 19 34.0 47 2.4

3 51 52 97 9.2 13 15.8 22 1.7

4 51 52 92 8.0 11 13.7 19 1.6

5 55 56 98 42.6 68 103.4 166 2.4

6 55 56 93 41.0 66 88.3 142 2.1

7 55 56 89 26.5 43 98.6 159 3.7

8 55 56 96 17.1 28 53.9 87 3.1

9 55 56 91 15.0 24 41.0 66 2.7

10 55 56 94 17.3 28 47.5 76 2.7

11 55 56 92 16.7 27 60.2 98 3.5

a. The measurements were carried out by GPC with THF as eluent and PS as standard.

b. PD = Mw/Mn


39

2.3. Synthesis of phosphonic acid functionalized monomer 60 and PPPs 61 and

62.

2.3.1. Synthesis of monomer 60.

The synthesis of an amphiphilic polymer with a pendant alkyl phosphonic acid group can be

used for the development of conducting polymers that form self-assembled monolayers or

multilayers with a simple dipping deposition method.[82] In fact, very recently, it was

demonstrated that under certain conditions irregular polythiophene phosphonic acids form

multilayers with zirconium.[83] In addition, polythiophene polyelectrolytes could be assembled

using a cation assembly mechanism.[84] In the present work, phosphonic acid was introduced as a

hydrophilic polymer side chain. The synthesis of monomer 60 started with the monoalkylation of

2,5-dibromobenzene-1,4-diol using Williamson’s etherification reaction in dry ethanol to afford

57 (Scheme 31).

CH3CNBrBr

OC6H13

HO

BrBr

OC6H13

O

BrBr

OC6H13

O

P OOO

OH

BrBr

OC6H13

O

I

57

58 59 60

tr iethyl phosphitePPh3

I2CH2Cl2

K2CO3

6-bromohexan-1-ol67% 84%

93%

Scheme 31: Synthesis of phosphonic acid functionalized monomer 60.

The addition of 6-bromohexan-1-ol to the monoalkylated building block 57 also followed the

mechanism of Williamson’s etherification synthesis, though the conditions were slightly

different. Further, the hydroxyl group was transformed to the iodide 59. Iodide was chosen

amongst all halogens because of its good leaving group ability (weak base). The mechanism of

this reaction follows the Mukaiyama redox-condensation reaction.[85] Finally, with triethyl

phosphite, 59 was transferred into phosphonate 60 which offered various possibilities to achieve

easily other interesting molecules. The reaction mechanism of this step follows the Michaelis-

Arbuzov reaction as shown in Scheme 32. It is a convenient synthetic method for the preparation


40

of alkyl phosphonic esters from alkyl halides and triethyl phosphite.[86] The first step involves

nucleophilic attack by the phosphorus on the alkyl halide, followed by the halide ion dealkylation

of the resulting trialkoxy-phosphonium salt.

POEt

EtO OEtI R P

EtO OEt

OR

+I-PO

EtO- EtBr R

EtO

Scheme 32: Mechanism of the Michaelis-Arbuzov reaction (R = alkyl, aryl or α-halo ester).[86]

2.3.2. Suzuki polycondesation

SPC of monomer 60 and its boronic ester counterpart 45 in THF/H2O using freshly prepared

Pd[P(p-tolyl)3]3 as catalyst precursor and NaHCO3 as base gave polymer 61 (Scheme 33). A

series of optimization experiments were carried out using standard SPC conditions by slightly

changing the mole ratio between the two monomers in order to achieve at least in a few cases a

precise 1:1 stoichiometry. Yields and molecular weights determined by GPC calibrated versus

polystyrene standards are summarized in Table 4.

Only low molecular weight materials were obtained after several experimentations. The

highest degree of polymerization for polymer 61 (entry 3, Table 4) was Pn = 25 (Mn = 13.2

kg/mol), Pw= 36 (Mw = 18.4 kg/mol). Hydrolysis of the phosphonic ester (polymer 61) with

bromotrimethylsilane and water led to a PPP with the phosphonic acid functionality (62). The

neutral polymer 62 was insoluble in any organic solvent as well as insoluble in water.

OC6H13

O

P OOO

n

OC6H13

O

P OHOOH

n

61 62

69 + 45

NaHCO3

Pd

THFH2O

(CH3)3SiBr

CH2Cl2CH3OH

89% 100%

Scheme 33: Synthesis of phosphonic acid functionalized polymers 61 and 62.


41

Table 4: Conditions used for the polymerization of monomer 60 using Pd[P(p-tolyl)3]3 as

catalyst precursor and average molecular weights of polymer 61 obtaineda

Entry Mn

[kg/mol]

Pn

Mw

[kg/mol]

Pw

Yield

[%] PDIb

1 7.4 14 16.9 32 88 2.2

2 4.0 8 8.4 16 96 2.1

3 13.2 25 18.4 36 91 1.3

4 7.9 15 13.4 26 93 1.6

5 10.0 19 15.5 30 84 1.5

6 10.3 20 14.4 28 91 1.3

7 4.6 9 8.8 17 89 1.9


b. PD = Mw/Mn

2.4. Amino-functionalized first and second generation dendritic PPPs. In the following, the synthesis of a series of orthogonally protected first and second generation

dendritic building blocks with amino functional groups at the periphery is described. For surface

coating applications, it was necessary to synthesize a polymer having a rigid rod poly(para-

phenylene) backbone with amino-functionalized groups on one side and water soluble oligo

(ethyleneoxy) chains on the another side as shown in Figure 11. This chapter will therefore not

only describe the synthetic aspects but will also give the results of the first measurement

regarding surface coating of the polymer obtained.

Water soluble OEG chains

Amino-functionalized group

Rigid rod PPP backbone

Surface Figure 11: Schematic representation of surface coatings of the poly(para-phenylene)s.


42

2.4.1. Synthesis of the amino-functionalized monomer 65

The synthetic sequence starts from the 2,5-dibromobenzene-1,4-diol 23, which carries

appropriate functions for both chain attachment and SPC. Monoalkylation of 23 was achieved by

statistical Williamson etherification NaOH in dry ethanol and gave 57 in 64% yield as shown in

Scheme 34. The first-generation (G-1) Boc-protected ester 63 was prepared according to

literature procedure.[87] Ester 63 was reduced with LiAlH4 to give the first-generation (G-1)

benzyl alcohol 64.[88] Mitsunobu reaction conditions (PPh3/ DEAD) were employed for the

coupling reaction of the monoalkylated building block 57 and G-1 benzyl alcohol 64 to form

monomer 65. Triphenylphospine oxide (TPPO) is the major side product in the Mitsunbo

reaction. The small amount of TPPO which could not be removed by column chromatography

was separated by repeated recrystallization.

BrBr

OH

HO

BrBr

OC6H13

HO

C6H13Br

dry ethanol64%

O

O

O

N

O

NO

H

H

BrBr

O

O

O

O O

OH

N

O

N

O

H H

O O

LiAlH4

THF79%

57DEAD

Ph3P67%

23 57

63 64 65

O O

O

N

O

N

O

H H

O O

O

Scheme 34: Synthesis of the amino-functionalized monomer 65.

The purity of dibromo monomer 65 was determined by high resolution NMR spectroscopy

and micro analysis. Figure 12 is a 500 MHz 1H NMR spectrum of monomer 65. The small peaks

at δ = 1.21, 3.70 and 4.32 ppm are from solvent impurities. These solvent impurities remain even

after drying the substance under high vacuum for several hours. In order to achieve a 1:1


43

stoichiometry, a series of optimization experiments were carried out using the monomers 45 and

65. Figure 13 is a 75.5 MHz 13C NMR spectrum of monomer 65. All peaks in the 13C NMR

spectrum could be assigned to the carbon atoms present in the monomer 65.

Figure 12: 500 MHz 1H NMR spectrum of monomer 65 in CDCl3 at 20 °C. Signals of traces of

solvents are marked (*).

Figure 13: 75.5 MHz 13C NMR spectrum of monomer 65 in CDCl3 at 20 °C.


44

2.4.2. Attempts for desymmetrization of hydroquinone

The stoichiometric reaction of 2,5-dibromobenzene-1,4-diol 23 with Boc-protected G-1

alcohol 64 using Mitsunobu reaction conditions (PPh3/DEAD), was expected to produce a

monosubstituted dibromohydroquinone adduct, but in contrast to expectations the disubstituted

product 68 was obtained. Desymmetrization of diol 23 was further carried out by changing the

stoichiometry of the starting materials 23 : 64 (1: 2.5, 1: 5.0) but only the disubstituted dibromo

hydroquinone 68 was formed as shown in Scheme 35.

BrBr

OH

HO

O

O

O

N

O

NO

H

H

BrBr

O

O

O

O O

OH

N

O

N

O

H H

O O

DEAD

Ph3P

73%

23 64 68

+

O

O

N

O

NO

O

O

H

H

Scheme 35: Synthesis of disubstituted amino-functionalized monomer 68.

The disubstituted dibromomonomer 68 was further converted into the corresponding polymer

using established SPC reaction conditions. Figure 14 shows the 126 MHz 13C NMR spectrum of

the disubstituted dibromomonomer 68.


45

Figure 14: 126 MHz 13C NMR spectrum of monomer 68 in CD2Cl2 at 20 °C.


Polymers 66 and 69 were obtained by SPC of monomers 65 and 68, respectively. The reaction

was carried out in THF/H2O using freshly prepared Pd[P(p-tolyl)3]3 as catalyst precursor and

NaHCO3 as base (Scheme 36). To meet the required exact 1:1 stoichiometry, a series of

polymerization experiments were carried out for each of the two monomer combinations in which

the molar proportions were slightly modified around the presumed matching point. In most cases,

virtually quantitative monomer conversion was reached. All polymers of 66 and 69 were obtained

as slightly blue shed colored, fibrolous materials after freeze-drying from benzene. The molecular

weights of polymer 66 and 69 determined by GPC against polystyrene (PS) standard are

summarized in Table 5. The deprotection of the dendronized amphiphilic polymers were carried

out using trifluoroacetic acid (TFA) to give the corresponding deprotected polymers 67 and 70.


46

97%

+ 45Pd

NaHCO3THF/H2O

90%

OX

YO

TFA

CH2Cl2n

OX

YO

Br Br

65 : X = R1, Y = R2

68 : X = Y = R2

66 : X = R1, Y = R2 67 : X = R1, Y = R3

69 : X = Y = R2 70 : X = Y = R3

O

O

NO

NO

H

H

O

R2 =R1 = C6H13

O

O

NH3+ CF3COO-

NH3+ CF3COO-

R3 =

O

OX

YO

n

Scheme 36: Synthesis of polymers 66, 67, 69 and 70.

If a large excess of the acid per protecting group was applied at room temperature to the

polymer in dichloromethane, a tbutyl signal with a very small intensity compared to the original

one of Boc remained in the 1H NMR spectrum. If the deprotection was first carried out in neat

TFA, followed by treatment in TFA and dichloromethane solution, even a highly amplified NMR

spectrum did not show any indication of a tbutyl signal anymore. Therefore, it can be concluded

that the deprotection was virtually quantitative.

Polymers 66, 67, 69 and 70 were investigated with high-resolution 1H and 13C NMR

spectroscopy to characterize their molecular structure. Figure 15 depicts the 500 MHz 1H NMR

spectrum of Boc-protected polymer 69 and its corresponding deprotected polymer 70.


47

Figure 15: 500 MHz 1H NMR spectrum of Boc-protected polymer 69 in CDCl3 (bottom) and its

corresponding deprotected polymer 70 (top) in CD3OD at 20 °C.

Both polymers are completely soluble in chloroform, CH2Cl2, THF and partially soluble in

toluene. To determine the molecular weights of polymer 66 and 69, GPC analyses were

performed in chloroform solutions on the basis of a calibration with polystyrene (PS) standards.

The maximum apparent number-average molecular weights (Mn’s) for 66 and 69 were 37.3 and

14.7 kg/mol, respectively (polymer yields were 96 and 94%, Table 5). Only for optimum SPC

conditions, high monomer conversions and high molar mass could be reached. Considering the

number of independent runs for each monomer, however, SPC worked considerably better for

monomer 65 than for 68 (with one exception, entry 2, Table 5). All polymers prepared showed

monomodular GPC curves. Two main conclusions can be drawn from Table 5: (a) high

molecular weight materials can be obtained; (b) Polymer yields are high throughout and usually

beyond 90 %.


48

Table 5: Conditions (catalyst precursor: Pd[P(p-tolyl)3]3) and average molecular weights of the

polymers 66 and 69 prepareda

Entry Monomer Polymer Mn

[kg/mol]

Pn

Mw

[kg/mol]

Pw

PDb

Nr [g] Nr Yield

[%]

1 65 0.5 66 93 26.5 38 50.2 72 1.8

2 65 0.5 66 97 11.9 17 20.8 30 1.7

3 65 0.5 66 96 37.3 53 88.0 125 2.3

4 65 0.3 66 88 33.9 48 58.9 84 1.7

5 65 0.25 66 94 14.7 21 39.4 56 2.6

6 68 0.5 69 97 21.4 20 32.3 31 1.5

7 68 0.5 69 90 17.2 17 30.7 30 1.7

8 68 0.5 69 98 15.4 15 19.3 19 1.2

9 68 0.49 69 94 32.8 31 35.8 34 1.0


b. PD = Mw/Mn

2.4.4. Desymmetrization: The key step in monomer synthesis

For desymmetrization of hydroquinone, a short alkyl chain was introduced as a spacer by

classical Williamson etherification reaction. 2,5-Dibromobenzene-1,4-diol 23 on stoichio-metric

reaction with 1,2-dibromoethane 71 gave 62% monoalkyl bromide as a colorless solid. Second-

generation (G-2), Boc-protected ester 73 was prepared following a reported protocol.[87] This

amino-functionalized dendritic G-2 ester was reduced with LiAlH4 and gave the dendritic G-2

benzyl alcohol 74. The Mitsunobu reaction of 2,5-dibromo-4-(2-bromoethoxy)phenol 72 with

amino-functionalized dendritic benzyl alcohol 74 and using PPh3/DEAD gave the dendritic

building block 76 as shown in Scheme 38. The small amount of TPPO that was not removed by

column chromatography was eliminated by repeated recrystallization.


49

O

O O

NHHN

OO

O

ONH

HN

O

NH

O NHO

O

NHBoc

NHBocNHBoc

NHBoc

O O

O

BrBr

OH

HO

+ BrBr BrBr

O

HO

Br

dry ethanol

NaoH

LiAlH4

THF

23 72

73 74

62 %

84 %

73

NHBoc

NHBocNHBoc

NHBoc

OH

71O

O

O

O

O

O

Scheme 37: Synthesis of building blocks 72 and 74.

The dendritic adduct 76 reacted with 1,3-bis(3,6,9-trioxadecanyl) glycerol 28 in the presence

of KOtBu yielding the β-elimination product 77 instead of the desired substitution product 78 as

shown in Scheme 38. In order to possibly obtain 78, several attempts were made by changing the

reaction conditions but in all cases β-elimination occurred and not the nucleophilic substitution

reaction. It may be that the nucleophilic attack was sterically hindered.

NHBoc

NHBocNHBoc

NHBoc

O KO tBu

THF

76

74

75 %

Br

BrO

Br

72 +

NHBoc

NHBocNHBoc

NHBoc

OBr

BrO

O

NHBoc

NHBocNHBoc

NHBoc

OBr

BrO

O O

OO

O O

OO

77 78

28DEAD

PPh3

73 %

Scheme 38: Attempts for the synthesis of amphiphilic monomer 78.


50

Figure 16 is the 300 MHz 1H NMR spectrum of the amino-functionalized G-2 olefin 77. The

inset shows signals for the cis and trans protons of 77 at chemical shift values δ = 4.5 and 4.7

ppm. Solvent signals are marked (*).

Figure 16: 300 MHz 1H NMR spectrum of G-2 olefin 77 in CDCl3 at 20 °C. (cis protons: j & k ,

trans protons: d & j)

In order to avoid the unwanted β-elimination the spacer was changed from ethyl to propyl.

The monoalkylated tribromide 80 was prepared in a similar way like Williamson’s etherification

reaction with 63% yield. Nucleophilic substitution was initially tried by using different solvents

as well as bases but neither substitution nor elimination could be observed. The nucleophilic

substitution reaction was finally carried out in presence of a large excess (80 mol%) of triethylene

glycol monomethyl ether and sodium metal. Purification was achieved by preparative gel

permeation chromatography (GPC) using chloroform as eluent, affording monoalkylated adduct

81 on the g scale as analytically pure material (63% yield). The amino-functionalized (G-2)

benzyl alcohol was converted into the corresponding (G-2) benzyl bromide 75 using carbon

tetrabromide and triphenyl phosphine.[89] The successive nucleophilic substitution reaction of the

monosubstituted building block 81 with amino-functionalized (G-2) benzyl bromide 75 was


51

carried out in the presence of K2CO3 and acetonitrile to give the designed amphiphilic

macromonomer 82 as shown in Scheme 39.

NHBoc

NHBocNHBoc

NHBoc

OH

CBr4

PPh3

74

78 %

NHBoc

NHBocNHBoc

NHBoc

OBr

BrO

NHBoc

NHBocNHBoc

NHBoc

Br

O

O

O

O

OBr

BrOH

OO

OOO

Br

BrOH

BrOHBr

BrOH

Br Br+NaOH

dry ethanol

Na

OEG63% 62%

K2CO3

acetonitr ile

73 %

81

75 82

23 79 80 81

Scheme 39: Synthesis of amphiphilic macromonomer 82.

Figure 17: 300 MHz 1H NMR spectrum of macromonomer 82 in CDCl3 at 20 °C.


52

The purity of the amphiphilic macromonomer 82 was confirmed by 1H NMR spectroscopy

and micro analysis. Figure 17 shows the 300 MHz 1H NMR spectrum of macromonomer 82. The

small peaks at δ = 0.9 and 1.2 ppm are due to solvent impurities. These solvent impurities remain

even after drying the substance under high vacuum for several hours.


Scheme 40 depicts the synthetic route to the amphiphilic polymer 83. Pd-catalyzed SPC of

monomers 82 and 45 in THF/H2O using freshly prepared Pd[P(p-tolyl)3]3 as catalyst precursor

and NaHCO3 as base gave polymer 83. Two experiments were performed between monomers 82

and 45, by slightly changing the mole ratio between the two monomers in order to achieve a 1:1

stoichiometry. For each experiment, about 500 mg of macromonomer 82 was used. The results of

the polymerization reactions are summarized in Table 6. The deprotection of the dendronized

amphiphilic polymer 83 was carried out using trifluoroacetic acid to give the corresponding

deprotected polymer 84 (Scheme 40). NHBoc

NHBoc

NHBoc

BocHN

O

97%

83

O

O

O

O

O

82 + 45 Pd

NaHCO3THF/H2O

90%

+H3NNH3

+

NH3+

NH3+

O

84

O

O

O

O

O

CF3COO-

CF3COO-

CF3COO-CF3COO-

TFA

CH2Cl2n n

Scheme 40: Synthesis of polymers 83 and 84.

Polymer 83 was insoluble in water and soluble in chloroform, CH2Cl2, THF and toluene. The

average molecular weights were determined by GPC against polystyrene standards. Polymer

yields were high and usually beyond 90%. Table 6 shows the molecular weights obtained for


53

polymer 83. Only low molecular weight products were obtained in both polymerization reactions.

The highest degree of polymerization for polymer 83 (entry 1, Table 6) was Pn = 3 (Mn = 5.0

kg/mol) and Pw= 5 (Mw = 7.6 kg/mol). In other words only oligomers were obtained.

Table 6: Conditions for polymerization of monomer 82 and 45 using Pd[P(p-tolyl)3]3 as catalyst

precursor and average molecular weights of polymer 83 obtaineda

Entry Mn

[kg/mol]

Pn

Mw

[kg/mol]

Pw

Yield

[%] PDb

1 5.0 3 7.6 5 93 1.5

2 3.2 2 4.7 3 91 1.4


b. PD = Mw/Mn

The deprotection of 83 gave completely water soluble oligomer 84, which was then used for the

first measurements regarding surface coating applications, see Figure 18.

2.4.6. An Optical Waveguide Lightmode Spectroscopy study of adsorbed oligomer

84

An Optical waveguide lightmode spectroscopy (OWLS) is based upon grating-assisted in-

coupling of a He-Ne laser into a planar waveguide coating and allows a direct online monitoring

of the “dry” mass of macromolecule adsorption, in that water that is hydrodynamically coupled

into adsorbates is not taken into account in mass detection. More detailed information on the

operational principles of OWLS are to be found in the literature.[90]

Figure 18 shows the graph of adsorbed mass against time. In this experiment (Optical Waveguide

Lightmode Spectroscopy, OWLS), a silica-coated waveguide was first exposed to an aqueous

buffer solution (pH 7).[90] After a stable baseline was obtained, an aqueous solution of polymer

84 was injected, (a in Figure 18). When the adsorption profile reached nearly a plateau (after ca.

30 min), the flow cell was rinsed with the buffer solution three times (b, c, d), and the mass of the

adsorbed amount of polymer was determined (e). Upon exposure of the polymer-coated

waveguide to serum (f) and subsequent rinsing (g) it was found that this low molecular weight


54

polymer 84 was not protein resistant (the amount of adsorbed proteins corresponds to h). This

was ascribed mainly to too short oligo ethyleneoxy chains, that could not generate a dense brush

structure.

Figure 18: In situ measurement of the adsorption of oligomer 84 and subsequent exposure to

human blood serum, monitored by OWLS. See text for details.

2.5. Fréchet type second generation (G-2) dendritic PPPs. 2.5.1. Monomer synthesis

The synthetic procedure to macromonomer 86 carrying two second-generation (G-2) Fréchet-

type dendrons is shown in Scheme 41. The choice of the particular dendritic fragments relies on

their well-established syntheses and the fact that their properties have been investigated probably

more than any other homologous and moreover they have been used preferably in most

dendronized macromolecular systems.[91] The stoichiometric reaction between 2,5-

dibromobenzene-1,4-diol 23 and Fréchet-type (G-2) dendron[92] 85 was carried out using

classical Williamson ether synthesis. One could expect the formation of the monodendritic

dibromohydroquinone adduct but only doubly substituted dibromohydro-quinone 86 was

obtained, as shown in Scheme 41. The macromonomer 86 was further converted into the

corresponding polymer 87 using established SPC reaction conditions.

-200

0

200

400

600

800

1000

1200

1400

1600

0 50 100 150 200 250

t [min]

ng/c

m2

Series1

a b c d

e

f g

h


55

OO

O

O

OO

O

Br

Br

O O

O

O

O O

O

+

86

O

OBr

O

O

O

O

OHBr

BrOH

85 23

K2CO3

acetonitri le

78%

Scheme 41: Synthesis of macromonomer 86.


Polycondensation of macromonomer 86 with benzene diboronic acid ester 45 was carried out

under standard SPC conditions using freshly prepared Pd[P(p-tolyl)3]3 as the catalyst precursors

(Scheme 42). The catalyst precursor was used immediately after recrystallization. A few

polymerization experiments were carried out using established SPC conditions by slightly

varying the ratio between the two monomers in order to achieve at least in a few cases a precise

1:1 stoichiometry. For each condition, about 500 mg of macromonomer was used, and a white,

fibrous material was obtained after freeze-drying from a benzene solution.

Polymer 87 was completely soluble in chloroform, CH2Cl2 and tetrahydrofuran. The average

molecular weights were determined by GPC against polystyrene standards. Again, like in the

case of the polymerization of 83, the results were not satisfactory for this dendritic

macromonomer. The highest degree of polymerization for polymer 87 was Pn = 6 (Mn = 10.2

kg/mol) and Pw= 11 (Mw = 17.4 kg/mol) with a polydispersity index of 1.7. Polymer 87 showed

bimodal GPC curve.


56

OO

O

O

OO

O

Br

Br

O O

O

O

O O

O

+

86

BBO

OO

O

O

O

OO

O

O

O

O

O

OO

O

O

O

n

NaHCO3

Pd

THF-H2O

87

4598 %

Scheme 42: Synthesis of polymer 87.

2.6. Determination of trace elements present in polymeric materials

2.6.1. Ligand Scrambling

The Suzuki cross-coupling as well as the Suzuki polycondensation reaction are carried out

using Pd(0) complexes as catalyst precursors which typically carry stabilizing phosphine ligands.

The catalytic cycle is believed to involve Pd(II) species (see Scheme 14). Recently, reports

appeared in the literature which shed light on potential side reactions of this cross-coupling.

Cheng and co-workers reported a facile aryl-aryl exchange reaction between the palladium center

and phosphine ligands in Pd(II) complexes.[93] Marcuccio and co-workers used this scrambling

effect to explain the synthesis of unsymmetrically substituted biaryls via Pd catalyzed coupling of

aryl halides with arylboronic acids to produce biaryl by-products, where one aryl was derived

from the phosphine ligand.[94] Methyl-phenyl exchange between palladium and a phosphine

ligand have also been observed in the related Stille cross-coupling.[95]

In low molar mass chemistry, this scrambling is disadvantageous but may be still acceptable

as long as the yields of side products are not too high and they can be separated off. In SPC,

however, aryl–aryl scrambling would be devastating. Novak et al.[96] pointed out that


57

phosphorus-containing groups could be incorporated not only as terminators 91 but also as

integral parts of the backbone 92. Previous work by Schlüter and co-workers[97] also confirmed

that phosphorus incorporation during SPC was a general phenomenon as shown in Scheme 43.

R1 Pd R2

PPh3

PPhPh

Ph

R1 Pd PhPPh3

PPhPh

R2

Ph Pd PhPPh3

PPh

R2R1

PPh

Ph

PPh

88 89 90

91

92

Scheme 43: Rationalization scheme explaining the phosphorus incorporation into polymeric

backbone during SPC.

2.6.2. Spectrophotometric detection of Pd(0) by using N,N-diethylphenylazothio-

formamide 95 as ligand

Synthetically it is not easy to remove „bound“ Palladium or Phosphorus from the polymeric

chain. Krebs and co-workers described a one pot synthesis of the N,N-diethylphenylazo-

thioformamide ligand 95[98] as shown in Scheme 44. This ligand is capable of dissolving free

palladium in an organic solvent. Complexation of the ligand 95 with Pd(0) results in a change in

color from light orange to dark brown-green. This change in color allows quantitative

determination of palladium by absorption measurements in the visible range of the spectrum at

800 nm. The method was applied for the catalyst used for the synthesis of PPPs namely Pd[P(p-

tolyl)3]3. Again a strong absorption maximum around 800 nm was observed, indicating that

remaining palladium catalyst possibly present in the polymer synthesized could be quantified

under the assumption that every Pd atom is chelated by the ligand.


58

NHNH2 NHNH

CS2

KOH

CH3I

Et2NH

Atm. O2

Pd(0)

NN

SNPd

NN

S N

0

NN

N

SS

S

NN

N

S

93 94 95

95 96

Scheme 44: Synthesis of ligand 95 and ligand-Pd complex 96.

In a first step, it was qualitatively confirmed that an absorption with a peak around 800 nm

occurs after treatment of the Pd catalyst with the N,N-diethyphenylazothioformamide ligand.

Figure 19 shows the UV/VIS spectra of ligand and Pd[P(p-tolyl)3]3 in THF. The catalyst-ligand

complex shows a moderately strong absorption with a maximum at 797 nm, while the ligand

alone does not absorb light above 600 nm, in analogy to what has been shown by Krebs and co-

workers.[98] Free palladium catalyst Pd[P(p-tolyl)3]3 did not show any peak around 800 nm. This

observation was a motivation to quantify the Pd content in some of the polymeric material

synthesized.

Two different sets of calibration experiments were first performed with a known amount of

palladium containing nanoparticles, one without any polymer and one in the presence of polymer.

Corresponding absorbance versus palladium catalyst concentration measurements allowed a

calibration for quantitative determination of the catalyst present as impurity in the polymer

synthesized. For details on the quantitative determination, calibration curves and VIS spectra of

polymer, please see experimental section (Chapter 5.3).


59

300 400 500 600 700 800 900 1000 11000.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

OD

(I =

1 c

m)

wavelength, nm

_________ Pure ligand_________ Pd-ligand complex

Pd(P(p-tolyl)3)3 in THF, 25 °C

Figure 19: UV/VIS spectra of ligand and Pd[P(p-tolyl)3]3 in THF recorded at 25 °C. The

catalyst-ligand complex shows a moderately strong absorption with a maximum at 797 nm, while

the ligand alone does not absorb light above 600 nm. Ligand: N,N-diethylphenyl-

azothioformamide.

In short, with the spectroscopic measurement described, one could have detected a peak

with an OD (l = 1 cm) > 0.005, corresponding to 1032 ppm. Since there was no such peak, one

can conclude that the catalyst content in the polymer sample was below ≈1000 ppm (= 0.1 wt %

= 0.023 mol %). Without dilution and with more polymer one may decrease the detection limit to

≈ 500 ppm (w/w). For lower Pd-contents and for the determination of „bound“ Pd, the

spectrophotometric method is, however, not sufficient.

Therefore, inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation-ICP-

MS as well-established methods for the accurate determination of even traces of elements in any

material were selected.


60

2.6.3. Determination of trace elements by inductively coupled plasma mass

spectrometry (ICP-MS) and laser ablation-ICP-MS

Inductively coupled plasma was developed in the early 80s and has been most successfully

applied to determine major, minor, trace and ultra trace elements in a wide variety of samples.

The low limits of detection and the more than 9 orders of magnitude linear dynamic range lead to

numerous applications of this technique in drinking water analysis, blood and biological and

medical samples, waste control, forensic applications and in all fields of geological samples.[99,

100] Solution nebulization ICP-MS requires however to dissolve the samples, which is in a lot of

cases time-consuming and can cause various contamination problems. Furthermore, some

samples (ceramic, polymers) are difficult to digest. Therefore, Gray[101] developed a new sample

introduction technique, which is based on laser ablation sampling of solid materials, which are

transported into the ICP-MS. The vaporization and ionization of the aerosol takes place in the

inductively coupled plasma. The ions generated are sucked into an interface, are separated via

m/z ratios and finally detected on a secondary electron multiplier. This technique became most

recently very popular, since accurate quantification has been demonstrated in a large number of

applications.[102] In geology, LA-ICP-MS is used to determine trace and ultra trace elements in

minerals and fluid inclusions.[103] The quantification is based on an external standard and internal

standardization.[104]

In the present work both techniques were applied for the determination of trace elements in

polymer samples. Therefore, the polymer sample was digested and the elements of interest were

analyzed by solution nebulization-ICP-MS. The instrument used for these studies was a

quadrupole ICP-MS (Perkin Elmer, Norwalk, USA). A second part of this sample was pressed

into a pellet and furthermore used as external calibration material for the direct solid trace

element determination.

The elements P, Pd, B, Na were analyzed using C as internal standard. However, the samples

were tested for more than 40 other isotopes, which were all below the typical limits of detection

in the single digit ppm range. Except for Na, where low concentrations and high standard

deviations were obtained, element concentrations were determined with an RSD of approx 10-

15%. Br, which was also of interest within the samples, was not quantitatively determined due to

the lack of an external standard. However, to give a relative information, cps and the ratio to P

are shown in Table 7.


61

Table 7: Concentrations of P, Pd, B, Na and Br/P ratios determined by laser ablation-ICP-MS

using an in-house prepared PPP standard and Carbon as internal standard.

Polymer P

ppm

Pd

ppm

B

ppm

Na

ppm

Br/P

(CPS)

40 4463 ± 259 81 ± 7 13.4±3.7 59.4±61 27452±1340

66 725 ± 69 1990±326 25±4.8 45±24 96293±7880

Table 7 shows the results of the quantitative analysis of two different polymers. In-house

prepared PPP standard and carbon as internal standard were used. Polymer 40 was treated with

ligand 95 for the removal of residual Pd (0). The palladium content was decreased down to 81±7

ppm. The Pd-content in 66 was 1990 ± 326 ppm. An ongoing study of removal of P and Pd traces

from the polymeric materials is a strong experimental challenge. The amount of catalyst used for

the SPC reaction plays a key role. Other possible elements from the polymeric samples were

reported with standard deviation values as shown in Table 7.


2.7.1. UV/VIS absorption properties of PPP 56

Conjugated polymers offer many advantages as materials for the use in blue light-emitting

diodes (LEDs).[105-107] Among the blue-emitting materials, poly(para-phenylene)s, PPPs, and

their derivatives are promising because of their high photoluminescence efficiency. They are

mechanically flexible, they can be fabricated in large areas and patterned with relative ease by

casting the semiconducting and luminescent polymer from solution, and the color of the emitted

light can be tailored by chemical modification of the molecular structure.

In the past few years the optical and electronic properties of alkyl and alkoxyl substituted

PPPs have been extensively studied.[108-111] The electronic spectrum of PPPs with alkoxyl chains

exhibits two bands. The one in the short wavelength region is assigned to absorptions of localized

chromophores, and the other in the long wavelength region is caused by π-π∗ transitions of

delocalized orbitals. The absorption maximum of the latter band depends on the torsion angle

between adjacent rings and shows a bathochromic shift with increasing degree of polymerization.


62

All poly(para-phenylene)s prepared were fluorescent. Polymer 56, a PPP with a chiral

substituent was investigated in detail. The UV/VIS absorption spectrum of polymer 56 was

recorded as a function of concentration using four different solvents: chloroform,

dichloromethane, tetrahydrofuran and toluene. In all four solvents, the absorption spectrum of

polymer 56 was rather similar with an almost identical position of the two maxima at ≈ 292 nm

and ≈ 350 nm (see Figure 20 and Table 8).

250 300 350 400 450 5000.0

0.2

0.4

0.6

0.8

1.0

1.2a

OD

(I =

1 c

m)

wavelength, nm

Polymer 56 in CHCl3, 25 °C

33 mg/L24.95 mg/L16.60 mg/L10.38 mg/L5.95 mg/L2.58 mg/L

250 300 350 400 450 5000.0

0.2

0.4

0.6

0.8

1.0 b

OD

(I =

1 c

m)

wavelength, nm

Polymer 56 in CH2Cl2, 25 °C

37 mg/L31.61 mg/L25.65 mg/L17.80 mg/L9.84 mg/L5.82 mg/L3.00 mg/L

250 300 350 400 450 5000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9c


Polymer 56 in Tetrahydrofuran, 25 °C

OD

(I =

1 c

m)

wavelength, nm

300 350 400 450 5000.0

0.2

0.4

0.6

0.8

1.0

1.2 d

OD

(l =

1 c

m)

wavelength, nm

Polymer 56 in toluene, 25 °C


Figure 20: UV/VIS spectrum of polymer 56 measured at different concentrations in four

different solvents at 25 °C: (a) chloroform; (b) dichloromethane; (c) tetrahydrofuran; (d) toluene.


63

Table 8: UV/VIS absorption maxima of polymer 56 determined in four different solvents.

Concentration range: ca. 2.5 – 35 mg/L (ca. 4 – 55 μM constitutional repeating unit), M

= 620 g/mol.

Wavelength

Chloroform Dichloromethane THF Toluene

λmax 1 (nm)

349.4 ± 0.2 350.7 ± 0.1 351.2 ± 0.3 350.1 ± 0.2

λmax 2 (nm)

292.1 ± 1.0 291.6 ± 0.1 292.5 ± 0.3 293.5± 0.7

Figure 21 illustrates determinations of the molar absorption coefficient (molar extinction

coefficient) ε of polymer 56 as determined in four different solvents for the two wavelengths at

which absorption was maximal. In the case of chloroform, dichloromethane and tetrahydrofuran,

the absorbance increased linearly with concentration. In the case of toluene (Figure 21d), there

was a clear deviation from linearity, indicating most likely polymer aggregation. Second

evidence for polymer aggregation in toluene stemed from the fact that polymer 56 was less

soluble in toluene than in chloroform, dichloromethane or tetrahydrofuran.


64

0 5 10 15 20 25 30 35 400.0

0.2

0.4

0.6

0.8

1.0

1.2a

λmax 2

292.6 nm

OD

(l =

1 c

m)

RMK-C*1 concentration, mg/L

λmax 1

349.4 nm

Polymer 56 in CHCl3, 25 °C

0 5 10 15 20 25 30 35 400.0

0.2

0.4

0.6

0.8

1.0b

λmax 2

291.6 nm

OD

(l =

1cm

)



λmax 1

350.6 nm

0 5 10 15 20 25 30 35 400.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8 c

λmax 2

292.5 nm

OD

(l =

1 c

m)


Polymer 56 in tetrahydrofuran, 25 °C

λmax 1

351.2 nm

0 5 10 15 20 25 30 35 400.0

0.2

0.4

0.6

0.8

1.0

1.2 d

λmax 1

393.4 nm

OD

(l =

1 c

m)


λmax 1

350.2 nm

Polymer 56 in Toluene, 25 °C

Figure 21: Absorbance versus concentration plots for polymer 56 measured at λmax1 and λmax2 in

(a) chloroform, (b) dichloromethane, (c) tetrahydrofuran, and (d) toluene.

Table 9 and 10 list molar extinction coefficient ε values of 56 determined in four different

solvents at different concentrations. The absolute value of the determined molar absorption

coefficient ε and not necessarily λmax is very sensitive to the purity of the sample and the precise

preparation of the solutions (e. g. concentration (wt/v), dilution of a stock solution). ε reflects

both the size of the chromophore and the probability that light of a given wavelength will be

absorbed when it strikes the chromophore.


65

Table 9: Molar absorption coefficient (molar extinction coefficient) ε of polymer 56 in

chloroform and dichloromethane.

Chloroform Dichloromethane

Concentration

(μM)

ε at

(349.4±0.2)

nm

(M-1 cm-1)

ε at

(292.1±1.0)

nm

(M-1 cm-1)

Concentration

(μM)

ε at

(350.7±0.1)

nm

(M-1 cm-1)

ε at

(291.6±0.1)

nm

(M-1 cm-1)

53.2 20,062 10,772 59.6 16,540 8,830

40.2 19,961 10,727 50.9 16,347 8,857

26.7 19,795 10,623 41.3 16,249 8,813

16.7 19,488 10,464 28.7 16,118 8,736

9.6 19,000 10,237 15.8 16,074 8,723

4.2 18,307 12,491 9.3 15,809 8,626

Table 10: Molar absorption coefficient (molar extinction coefficient) ε of polymer 56 in

tetrahydrofuran and toluene.

Tetrahydrofuran Toluene

Concentration

(μM)

ε at

(351.2±0.3)

nm

(M-1 cm-1)

ε at

(292.5±0.3)

nm

(M-1 cm-1)

Concentration

(μM)

ε at

(350.1±0.2)

nm

(M-1 cm-1)

ε at

(293.5±0.7)

nm

(M-1 cm-1)

53.2 14,359 7,622 54.8 18,704 9,760

37.2 14,247 7,591 40.1 18,266 9,608

26.3 14,036 7,482 29.6 17,560 9,243

13.6 13,895 7,483 16.2 16,149 8,456

7.4 13,744 7,439 9.9 14,689 7,184

3.7 13,191 7,227 4.6 13,008 6,273

Figure 22 is a plot of λmax1 and λmax2 versus ET(30), the solvent polarity parameter. ET(30) is a

measure of the polarity of a solvent. ET(30) is based on the transition energy for the longest-

wavelength solvatochromic absorption band of a compound that was labelled „dye no. 30“ in the


66

original reference.[112] For polymer 56, the determined λmax1 and λmax2 were independent on

ET(30).

33 34 35 36 37 38 39 40 41280

300

320

340

360

CHCl3 39.1

THF 37.4

CH2Cl2 40.7

Toluene 33.9 ET(30), kcal/mol

λmax

Polymer 56

N+

O-

“ dye no. 30 ” (see ref. 112)

Figure 22: Dependency of λmax1 and λmax2 of polymer 56 on the solvent polarity parameter

ET(30).

2.5.2. Fluorescence spectroscopy

The fluorescence emission and excitation spectra of polymer 56 dissolved in four different

solvents were measured at 25 °C as a function of polymer concentration (Figure 23 and 24). In all

solvents, including toluene, the emission maximum (λem, max) was at 419 nm and the excitation

maximum (λex, max) at 352 nm. Figure 23 shows the emission spectrum of polymer 56 measured in

chloroform, dichloromethane, tetrahydrofuran and toluene.

300 350 400 450 500 550 6000.0

2.0x105

4.0x105

6.0x105

8.0x105

1.0x106

1.2x106

1.4x106

1.6x106

a Polymer 56 in CHCl3 25 °C

excitation at 291 nm


1.15 mg/L ________0.64 mg/L ________0.30 mg/L ________

rela

tive

fluor

esce

nce

inte

nsity

wavelength, nm

300 350 400 450 500 550 6000.0

2.0x105

4.0x105

6.0x105

8.0x105

1.0x106

1.2x106

1.4x106

1.6x106

1.8x106b



2.00 mg/L __________0.60 mg/L __________0.30 mg/L __________

Polymer 56 in CH2Cl

2, 25 °C

rela

tive

fluor

esce

nce

inte

nsity

wavelength, nm


67

300 350 400 450 500 550 6000

2x105

4x105

6x105

8x105

1x106

1x106

1x106

c Polymer 56 in THF, 25 °C



1.20 mg/L _________0.70 mg/L _________0.40 mg/L _________

rela

tive

fluor

esce

nce

inte

nsity

wavelength, nm300 350 400 450 500 550 600

0.0

5.0x105

1.0x106

1.5x106

2.0x106

2.5x106

d



1.77 mg/L ________0.88 mg/L ---------------0.33 mg/L .................


rela

tive

fluor

esce

nce

inte

nsity

wavelength, nm

Figure 23: Concentration dependency of the emission spectrum of polymer 56 measured in (a)

chloroform; (b) dichloromethane; (c) tetrahydrofuran; (d) toluene. The excitation wavelength was

either 291 nm or 350 nm. T = 25 °C.

280 300 320 340 360 380 4000.0

2.0x104

4.0x104

6.0x104

8.0x104a Polymer 56 in CHCl

3, 25 °C

emission at 420 nm

1.20 mg/L _________0.70 mg/L _________0.30 mg/L _________

abso

rban

ce

wavelength, nm

280 300 320 340 360 380 4000.0

2.0x104

4.0x104

6.0x104

8.0x104

1.0x105

b

emission at 420 nm


2.00 mg/L__________0.60 mg/L __________0.30 mg/L __________

abso

rban

ce

wavelength, nm

280 300 320 340 360 380 4000

1x104

2x104

3x104

4x104

5x104

6x104

7x104

c

emission at 420 nm

Polymer 56 in THF, 25 °C

1.20 mg/L _________0.70 mg/L _________0.40 mg/L _________

abso

rban

ce

wavelength, nm

280 300 320 340 360 380 4000.0

2.0x104

4.0x104

6.0x104

8.0x104

1.0x105

1.2x105

1.4x105

d

emission at 420 nm

1.80 mg/L __________0.90 mg/L __________0.30 mg/L __________


abso

rban

ce

wavelength, nm

Figure 24: Concentration dependency of the excitation spectrum of polymer 56 measured in (a)

chloroform, (b) dichloromethane, (c) tetrahydrofuran, and (d) toluene. The emission wavelength

was 420 nm. T = 25 °C.


68

One parameter that characterizes fluorescence spectra is the so-called Stokes shift, the gap

between the maximum of the first absorption band and the maximum of the fluorescence

spectrum, expressed in cm-1. Polymer 56 exhibited a Stokes-shift of 4,760 cm-1[Δν = 1/(350·10-7

cm) – 1/(420·10-7 cm)]. This shift value is comparable to that of p-terphenyl and p-quaterphenyl.

Vahlenkamp and Wegner reported a Stokes-shift of about 3000 cm-1 for dialkoxy PPPs.[113]

UV/VIS and fluorescence measurements indicated that polymer 56 is a stiff polymer. The

chemical nature of the solvent had little influence on the fluorescence properties. Two adjacent

benzene rings are likely to be„twisted“, like in the case of biphenyl. There is no extensive

conjugation along the polymer backbone.

Chapter 3 Synthesis and characterization of poly(meta-phenylene)s by SPC

69

3. Synthesis and Characterization of Poly(meta-phenylene)s (PMPs)

by SPC

3.1. General considerations SPC has been developed into a key route for the synthesis of structurally defined polyarylenes.

By far, most polymers prepared by this method are poly(para-phenylene)s, which were

investigated principally because of their rigid-rod nature and their useful electro-optical

properties.[11a, 13] More recently, this synthetic route found its way into technical scale

applications aimed at preparing organic light-emitting diodes (OLEDs) based on linear

polyfluorene copolymers.[114]

Polyarylenes are chemically and thermally robust and interesting polymeric materials. This, of

course, is also true for the meta-linked polyphenylenes. Their kinked structure should not only

impart enhanced processability to the polymer – as found for the related meta-analogs of

aromatic polyamides (aramids) and thermotropic polyesters[115, 116] – but also is likely to permit

formation of highly amorphous materials because macromolecular ordering kinetics are expected

to be slow relative to typical processing time scales. Only a few reports described the synthesis of

PMPs but most of them yield low molecular weight materials, with little detail about the

properties of the materials produced.[24-29, 117]

In the present work, simple and very efficient synthetic strategies are presented to access

meta-monomers carrying flexible alkoxy or oligoethyleneoxy chains. It also describes SPC of

these meta-monomers which led to the corresponding poly(meta-phenylene)s. For this rather new

class of polyarylenes first property investigations were done for a specific representative.

3.2. PMPs carrying flexible alkoxy chains

3.2.1. Synthesis of meta-monomers carrying alkoxy chains Different alkoxy substituted chains were attached to 3,5-dibromophenol using classical

Williamson’s ether synthesis. As shown in Scheme 45, three different meta-dibromo monomers

were synthesized starting from the commercially available 3,5-dibromophenol 97. Williamson’s

etherification reaction of 97 with 1-bromopropane, 1-bromobutane and 1-bromohexane gave

meta-dibromo monomers 98, 100 and 102 respectively. In each monomer synthesis, large excess

amounts of alkyl bromide was used for complete conversion of 3,5-dibromophenol into the


70

corresponding meta-monomers. The excess amounts of alkyl bromides were removed simply by

evaporating and drying the substance under high vacuum for several hours. Small amounts of

alkyl bromides and colored impurities were removed by silica gel column chromatography using

hexane/ethyl acetate as eluent. The synthesis of monomer 102 was previously reported using

K2CO3 in diethyl ketone.[118]

BrBr

O

BrBr

OH

BrBr

O

BrBr

O

10098 97

102

NaOHNaOH

NaOH

C4H9BrC3H7Br

C6H13Brdry ethanol

dry ethanol dry ethanol

84%

87%89%

Scheme 45: Synthesis of three different meta-monomers 98, 100 and 102.

Figure 25: 500 MHz 1H NMR spectrum of meta-monomer 100 in CDCl3 at 20 °C. Insets are

corresponding amplified signals.


71

The purity of all meta-dibromo monomers were determined by high resolution 1H and 13C

NMR spectroscopy and micro element analysis. Figure 25 shows a 500 MHz 1H NMR spectrum

of monomer 100 in CDCl3 with insets for amplified regions of all signals. Most of the amplified

peaks showed corresponding carbon satellite signals, however, the small peaks at δ = 6.8 ppm

and δ = 7.2 ppm were from starting material. These small peaks were compared with the carbon

satellite signals of proton b. From this comparison and considering the natural abundance of 13C

of 1%, the purity of meta-monomer 100 was determined to be beyond 99.5%. Figure 26 shows a

representative 126 MHz 13C NMR spectrum of the same monomer in CDCl3.

Figure 26: 126 MHz 13C NMR spectrum of meta-monomer 100 in CDCl3 at 20 °C.

3.2.2. Suzuki polycondensation (SPC) SPC of meta-dibromo monomers 98, 100 and 102 with aryl diboronic acid esters 45 were

usually carried out in a two-phase solvent system (THF/H2O) and NaHCO3 as base (Scheme 46).

Freshly prepared Pd[P(p-tolyl)3]3 was used as a catalyst precursors. The catalyst precursor was

used immediately after recrystallization. A series of polymerization experiments were carried out

according to the synthetic procedure described in Chapter 2.2.5. SPC of meta-monomer 100 with

45 was carried out successfully on a 13.65 g scale.


72

Br

Br

OR

45

NaHCO3

THF/H2O~ 90 %

OR

BBO

O O

O+

Pd[P(p-tolyl)3]3

98 : R = C3H7

100 : R = C4H9

102 : R = C6H13

n

99 : R = C3H7

101 : R = C4H9

103 : R = C6H13 Scheme 46: Synthesis of poly(meta-phenylene)s 99, 101 and 103. During the polymerization reaction of monomer 98 with aryl boronic acid ester 45, a white

precipitate was formed in the reaction mixture. The white material was completely insoluble in

any organic solvent. However, a small amount of a THF- soluble fraction was collected in low

yield. The main reason behind the poor solubility of the white powder 99 may be due to the short

length of the alkoxy chain. The soluble part was used for the characterization of 99. The

molecular weight of the THF-soluble part was determined by GPC against polystyrene standards,

and it was found that only hexamers were present with a yield of 11%. Surprisingly, if the alkoxy

chain was switched from propoxy to butoxy, the material formed was completely soluble in

organic solvents. The largest series of experiments were performed with meta-monomers 100 and

102 to furnish corresponding polymers 101 and 103. These experiments are therefore described

in more detail.

3.2.3. Determination of Molecular Weights The polymers 101 and 103 were completely soluble in THF, CH2Cl2 and CHCl3 and partially

soluble in toluene. The reproducibility of the experiments was satisfactory and the results are

summarized in Table 11.

The average molecular weights were determined by GPC calibrated vs polystyrene standards.

The highest degree of polymerization for polymer 101 (entry 2, Table 11) was Pn = 312 (Mn =

69.9 kg/mol), Pw= 818 (Mw = 183.2 kg/mol) and for polymer 103 (entry 9, Table 11) was Pn = 85

(Mn = 21.4 kg/mol), Pw= 234 (Mw = 59.0 kg/mol). Polydispersities of the polymers 101 and 103

were in the range of 2.3–5.4 (except entry 12 which had a PDI value of 8.8). It should be

mentioned that most of the polymers prepared formed transparent films with high mechanical

strength, which is an independent indication of the materials high molar mass. The films were

obtained by simple solution casting technique.


73


polymers 99, 101 and 103a

Entry Monomer PolymerYield

[%]

Mn

[kg/mol]

Pn

Mw

[kg/mol]

Pw

PDb

Nr [g] 1 98 0.5 99 11c 1.3 6 1.8 8 1.3

2 100 0.5 101 94 69.9 312 183 818 2.6

3 100 2.0 101 93 26.8 120 89.7 400 3.3

4 100 5.0 101 97 11.0 49 59.9 267 5.4

5 100 2.0 101 90 13.1 58 48.5 216 3.7

6 100 5.0 101 98 25.5 114 83.0 370 3.2

7 100 5.0 101 96 13.2 59 45.6 203 3.4

8 100 13.6 101 97 27.8 125 64.9 290 2.3

9 102 0.5 103 97 21.4 85 59.0 234 2.7

10 102 1.0 103 91 14.2 57 55.7 221 3.9

11 102 0.5 103 93 11.1 44 49.1 195 4.4

12 102 0.5 103 94 7.6 30 67.1 264 8.8


b. PD = Mw/Mn

c. THF soluble fraction

The following three conclusions can be extracted from Table 11: (a) high molecular weight

materials can be obtained by SPC (entries 2, 3, 6 and 8 for polymer 101 and entries 9, 10 and 12

for polymer 103); (b) Polymer yields are high throughout and usually beyond 90%; (c) SPC of

monomer 100 was carried out on scale up to 13.65 g and most of the reactions yielded high

molecular weight polymers. This proves that SPC is a powerful step growth polymerization

reaction for the synthesis of polyarylene and related polymers on a scale of several grams.

Few polymer samples were provided to Prof. Paul Smith, ETH Zurich for studying the

polymer’s thermal and mechanical properties. Preliminary results are quite promising but due to

their relatively low molar masses, melt-compression-molded films of the polymer samples


74

displayed such brittleness that their mechanical properties could not be tested in a reliable

manner. This motivated us to fractionate the polymers by precipitation and again to check the

mechanical properties of the high molecular weight fraction. All PMPs prepared showed

transparent blue emitting films with an intense grewish color. Polymer 101 (entry 6, Table 11)

was choosen for the removal of colored impurities and fractionation by precipitation. For

purification, polymer 101 was dissolved in THF and N,N-diethyl-2-phenylhydrazinecarbo-

thioamide 95 was added to remove residual Pd traces. The resulting dark solution was stirred at r.

t., which did not lead to any significant color change. The polymer 101 was then precipitated by

the addition of methanol from CH2Cl2 solution and three different molecular weight fractions

were collected. For the detailed fractionation procedure, see Chapter 5.2.3. The quantities and

molar masses of the fractions are shown in Table 12. Fraction 1 was subjected to four consecutive

precipitations in order to improve on its color. After this treatment the polymer had an almost

white appearance. The losses of material were estimated to be 10-15 %. All bulk

characterizations were done with this highly purified material.

Table 12: Weight-average molar masses (Mw) and degrees of polymerization (Pw) from gel

permeation chromatography of PMP 101 and its three fractions referenced to polystyrene

standards. The polydispersities are 3.3 for the as-obtained material and approximately 2 for the

fractions.

PMP

(101)

Amount

[g] Mw Pw

As obtained 3.57 83000 370

Fraction 1 1.08 254700 1137

Fraction 2 1.42 85100 380

Fraction 3 0.98 26500 119

The purity of all polymers was determined by high resolution 1H and 13C NMR spectroscopy

and micro analysis. All polymers gave perfect or near-perfect results from combustion analysis

(see Experimental section). Figure 27 shows a 700 MHz 1H NMR spectrum of polymer 101

(fraction 1, Table 12) in CDCl3 with signal assignments to illustrate the level of structural

integrity. The inset shows the aromatic region. All signals are broad and there is no sign of end


75

groups which is an independent indication of the material’s high molecular weights. Figure 28 is

a representative 176 MHz 13C NMR spectrum of polymer 101 in CDCl3.

Figure 27: 700 MHz 1H NMR spectrum of polymer 101 (fraction 1) in CDCl3 with signal

assignment to illustrate the level of structural integrity. The inset shows the amplified aromatic

region. Solvent signals are marked (*).

Figure 28: Representative 13C NMR spectrum (176 MHz) of polymer 101 (fraction 1) in CDCl3

with signal assignment. Solvent signals are marked (*).


76

3.2.4. Synthesis of meta-monomer 108 The synthesis of monomer 108 started with the commercially available 4-aminobenzoic acid

ethyl ester 104 which was brominated to 105[119] and then desaminated to 106,[120] followed by the

reduction of the product to its alcohol 107 with lithium aluminium hydride in dry diethyl ether

(Scheme 47). The meta-monomer 108 was easily synthesized from (3,5-dibromo-

phenyl)methanol 107 and hexyl bromide in the presence of sodium hydride as a base.[121] A large

excess amount of hexyl bromide was used for the etherification reaction. The monomer 108 was

purified twice by column chromatography through silica gel and the purity of the meta-monomer

108 was confirmed by high resolution 1H and 13C NMR spectroscopy and correct values from

micro-analysis.

Br

Br

O

Br

Br

HO

Br

Br

EtOO

LiAlH4

106 107 108

NaH

THFhexyl bromide

84 %

THF78 %Br

Br

EtOO

HNO2

105

EtOHH2N

EtOO

104

H2N

Br2

Scheme 47: Synthesis of dibromo monomer 108.

Figure 29 shows the 700 MHz 1H NMR spectrum of monomer 108 in CDCl3. The inset shows

the amplified aromatic region with 13C satellite signals marked (*). The amplified aromatic

region showed small amount of impurities at δ = 7.9, 8.0 and 8.1 ppm. These impurity signals

belong to the starting material 106 which could not be removed by repeated column

chromatography. These impurity signals were compared with 13C satellite signals. From this

comparison and considering the natural abundance of 13C of 1%, the purity of meta-monomer

108 was determined to be beyond 99.5%.


77

Figure 29: 700 MHz 1H NMR spectrum of monomer 108 in CDCl3 with signal assignment to

illustrate the level of structural integrity. The inset shows the amplified aromatic region with 13C

satellites signals marked (*).


Polymers 109 and 110 were obtained by SPC of monomer 108 with aryl boronic acid esters 45

and 48, respectively, in THF/H2O using freshly prepared Pd[P(p-tolyl)3]3 as catalyst precursor

and NaHCO3 as base (Scheme 48). To meet the required exact 1:1 stoichiometry, a series of


the molar proportions were slightly modified around the presumed matching point. In most cases,

virtually quantitative monomer conversion was reached. Both the polymers 109 and 110 were

obtained as slightly blue shed colored, fibrolous materials after freeze-drying from benzene.

*

8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 ppm

7 . 47 . 67 .88. 0 p p m

* **

CHCl3

H2O

Br

OC6H13

Br

* 13C satellites

Br

CO2Et

Br

< 0.5 %


78

45 : R = H

48 : R = C6H13

NaHCO3

THF/H2O~ 90 %

BBO

O O

O+

Pd[P(p-tolyl)3]3

nBr

Br

O

108

OR

R

R

R

109 : R = H

110 : R = C6H13 Scheme 48: Synthesis of poly(meta-phenylene)s 109 and 110.

Polymers 109 and 110 were investigated with high-resolution 1H and 13C NMR spectroscopy

to characterize their molecular structure. Figure 30 depicts the 500 MHz 1H NMR spectrum of

polymer 109 in CDCl3 with signal assignment to illustrate the level of structural integrity. All

signals are broad as shown in Figure 30. Figure 31 represents corresponding 176 MHz 13C NMR

spectra of polymer 109 in CDCl3.

Figure 30: 500 MHz 1H NMR spectrum of polymer 109 in CDCl3 with signal assignment.

Solvent signals are marked (*).


79

Figure 31: Representative 13C NMR spectrum (126 MHz) of polymer 109 in CDCl3 with signal

assignment.

Both polymers were completely soluble in chloroform, CH2Cl2, THF and partially soluble in

toluene. To determine the molecular weights of polymer 109 and 110, GPC analyses was

performed in chloroform solutions on the basis of a calibration with polystyrene (PS) standard.

The results and yields of polymers 109 and 110 are summarized in Table 13. The maximum

apparent number-average molecular weights (Mn’s) for polymer 109 and 110 were 43.8 and 12.9

kg/mol, respectively (polymer yields were 89 and 93%, Table 13). Only for optimum SPC

conditions, high monomer conversions and molar masses could be reached. Considering the

number of independent runs for both monomers, however, SPC worked considerably better for

monomer 45 than for monomer 48.

The following three conclusions can be drawn from Table 13: First, high molecular weight

materials could be obtained. Second, polymer yields were high throughout and usually beyond

90%. Third, both polymers exhibited a polydispersity index usually in the range of 1.8–4.7

(except for entry 2 which had a PDI value of 6.5).


80


polymer 109 and 110 obtaineda

Entry Monomer Polymer Yield

[%]

Mn

[kg/mol]

Pn

Mw

[kg/mol]

Pw

PDb

Nr [g] 1 108 0.5 109 84 33.4 124 156.4 583 4.6 2 108 0.5 109 93 8.1 30 52.7 196 6.5 3 108 1.0 109 91 9.5 36 45.7 172 4.7 4 108 0.5 109 88 13.5 51 30.2 114 2.2 5 108 2.0 109 96 6.7 25 30.6 115 4.5 6 108 1.0 109 89 43.8 165 80.0 300 1.8 7 108 0.5 109 93 13.5 51 30.2 114 2.2 8 108 0.5 109 92 11.6 44 48.6 183 4.1 9 108 0.5 110 89 12.8 29 30.0 67 2.3 10 108 0.48 110 92 12.9 29 37.9 87 2.9


b. PD = Mw/Mn

Most of the polymers prepared showed bimodular GPC curves as shown in Figure 32a. Due to

their relatively low molar mass shoulder in GPC curve (Figure 32a), melt-compression-molded

films of polymer samples displayed such brittleness that their mechanical and thermal properties

could not be tested in a reliable manner. Therefore, polymer 109 was fractionated in methanol

from CH2Cl2 solution and two different molecular weight fractions were collected (Figure 32b

and 32c). High molecular weight fraction 1 (Figure 32b) was used for the characterization of the

molecular structure. The low molecular weight fraction 2 (Figure 32c) was collected. It

corresponded to roughly 15-18% of the total amount of polymers formed. For detailed

fractionation procedure, see the Experimental Section (Chapter 5.2.3).


81

a)

b)

c)

Figure 32: Fractionation of polymer 109 by precipitation in CH3OH from CH2Cl2 solution a)

GPC curve of raw polymer 109; b) high molecular weight fraction 1 (~ 85% of the total amount

of polymer formed); c) low molecular weight fraction 2 (~ 15% of the total amount of polymer

formed). 1: Viscosity detector, 2: Refractive index detector, 3: Calibration with PS standard, 4:

Reference peak (Toluene).

3.3. Co-polymerization

Co-polymerization is the term used for simultaneous polymerization of two or more

monomers. As described in Chapter 3.2.2., SPC applied to meta-monomer 98 and aryl boronic

acid esters 45 results in an insoluble white precipitate. In order to avoid the solubility problem, a

co-polymerization reaction of meta-monomer 98 was carried out with para-dibromo monomer 46

and aryl boronic acid ester 45. The stoichiometry of para- monomers to meta- monomers was

exactly 1:1. Scheme 49 depicts the synthetic route to the amphiphilic polymer 111. A series of

optimization experiments were carried out according to the synthetic procedures described in

Chapter 2.2.5. For each experiment, about 250 mg of meta-monomer 98 was used.


82

Br

45

NaHCO3

THF/H2O98 %

O

BBO

O O

O+

Pd[P(p-tolyl)3]3

n

Br

Br

O

+Br

m

46 111

98

Scheme 49: Synthesis of poly(meta-phenylene)s 111.

Polymer 111 was completely soluble in chloroform, CH2Cl2 and THF and partially soluble in

toluene. The results of the copolymerization reactions are represented in Table 14. The average

molecular weights were determined by GPC against polystyrene standards. Copolymerization

yields were high, usually more than 90%. Table 14 shows molecular weights obtained for

polymer 111. The highest degree of polymerization for polymer 111 (entry 1, Table 14) was Pn =

17 (Mn = 7.8 kg/mol), Pw= 94 (Mw = 42.8 kg/mol). It should be mentioned that both polymer

samples prepared formed transparent films with considerable mechanical strength, which was an

independent indication of the polymers relatively high molar mass. The purity of polymer 111

was confirmed by high resolution NMR spectroscopy and micro analysis.

Table 14: Conditions for polymerization of monomers 45, 46 and 98 using Pd[P(p-tolyl)3]3 as

catalyst precursor and average molecular weights of polymer 111 obtaineda

Entry Mn

[kg/mol]

Pn

Mw

[kg/mol]

Pw

PDb

Yield

[%]

1 7.8 17 42.8 94 5.5 98

2 8.5 19 22.8 50 2.6 92


b. PD = Mw/Mn


83

3.4. PMPs carrying water soluble OEG chains To improve the solubility of the PMPs in water, the alkyl side chains were replaced by oligo

ethylene glycol (OEG) moieties. These OEG chains are often used to obtain water-soluble

polymers, therapeutic agents and nanoparticles.[122, 123] Poly- and oligo-(ethylene glycols) (PEG

and OEG) are also frequently used as spacers for bioconjugates.[124, 125] The linear OEG chains

are commercially available whereas for branched OEG chains, several synthetic protocols are

available that lead to the product in a few steps.[21]

3.4.1. Synthesis of meta-monomers carrying water soluble OEG chains The synthetic sequence for 113 started from (3,5-dibromophenyl)methanol 107. Compound

107 was converted into 3,5-dibromobenzyl bromide 112 on a large scale according to a protocol

reported in the literature.[126] The nucleophilic substitution reaction of tribromide 112 with the

branched OEG chain 28 in the presence of KOtBu afforded monomer 113 in 76% yield as shown

in Scheme 50. The product purified twice by silica gel column chromatography and the achieved

purity was determined by high resolution 1H and 13C NMR spectroscopy and correct values from

micro-analysis.

Br

Br

Br

Br

Br

O

O

O

Br

Br

HO

107 112 113

76 %

O

O

OO

OO

KOtBu

THF

28PBr3

Diethyl ether83 %

Scheme 50: Synthesis of meta-dibromo monomer 113.


SPC of meta-monomers 113 and 115[127] were carried out under standard conditions with

benzene boronic acid ester 45 using freshly prepared Pd(PPh3)4 or Pd[P(p-tolyl)3]3 as catalyst

precursors and tetrabutylammonium bromide as an additive (Scheme 51). The catalyst


84

precursors were used immediately after recrystallization. To meet the required exact 1:1

stoichiometry of the monomers, a series of polymerization experiments were carried out with

slightly varying monomer ratios; for each experiment of polymer 114 and 116, about 500 mg of

dibromo monomer was used (Table 15). Polymer 116 gave perfect or near-perfect results with

respect to the calculated values from combustion analysis whereas for the polymer 114, the

expected value for carbon was off by more than two percent, which can be attributed to the

relatively low molar mass of polymer 114.

Br

Br

113 : x = R1

O O

OO

O

OO

O

BBO

OO

O

XO XO

n

+NaHCO3

THF/H2O~ 90 %

Pd[P(p-tolyl)3]3

115 : X = R2

OO O

R1 =

R2 =

114 : x = R1

116 : X = R2

45

Scheme 51: Synthesis of poly(meta-phenylene)s 114 and 116.

Figure 33: 500 MHz 1H NMR spectrum of polymer 116 in CDCl3 with signal assignment.

Solvent signals are marked (*).


85

Polymers 114 and 116 were investigated with high-resolution 1H and 13C NMR spectroscopy

to characterize their molecular structure. Figure 33 shows the 500 MHz 1H NMR spectrum of

polymer 116 in CDCl3 with signal assignment to illustrate the level of structural integrity. All

signals are broad as shown in Figure 33. All the solvent peak impurities at δ = 0.9, 1.2 and 2.4

ppm appeared even after drying the polymer under high vacuum for several hours.

Both polymers were completely soluble in chloroform, CH2Cl2, THF and partially soluble in

toluene. The average molecular weights were determined by GPC against polystyrene standards.

The highest degree of polymerization for polymer 114 (entry 3, Table 15) was Pn = 15 and (Mn =

8.3 kg/mol), Pw= 60 (Mw = 33 kg/mol) and for polymer 116 (entry 6, Table 15) Pn = 33 (Mn =

10.7 kg/mol), and Pw= 64 (Mw = 20.9 kg/mol). Polydispersity for both the polymers (114 and

116) were in the range of 1.4–4.0.

The following three conclusions can be drawn from Table 15: a) The polymer yields were

high throughout and usually around 90%; b) To obtain high molecular weight polymers Pd[P(p-

tolyl)3]3 was the better catalyst precursor as compared to Pd(PPh3)4; c) Only for optimum SPC

conditions, high monomer conversion and high molar mass could be reached.

Table 15: Conditions and average molecular weights of polymers 114 and 116a.

Entry Monomer Catalyst

precursors

Polymer Mn

[kg/mol]

Pn

Mw

[kg/mol]

Pw

PDb

Nr Yield

[%]

1 113 c 114 88 6.9 13 9.8 18 1.4

2 113 c 114 84 8.2 15 13.4 24 1.6

3 113 d 114 93 8.3 15 33.0 60 4.0

4 113 d 114 91 8.6 16 18.2 33 2.1

5 113 d 114 89 12.2 23 20.3 39 1.7

6 115 d 116 92 10.7 33 20.9 64 1.9

7 115 d 116 98 6.1 17 11.5 35 1.8


b. PD = Mw/Mn

c. Freshly prepared Pd(PPh3)4


86

d. Freshly prepared Pd[P(p-tolyl)3]3

3.4.3. Synthesis of a meta-monomer carrying two water soluble OEG chains

The synthetic route for disubstituted meta-monomer 120 was started with the commercially

available triethylene glycol monomethyl ether 25 (Scheme 52). The free hydroxyl group of the

OEG ether 25 was protected with tosyl chloride in tetrahydrofuran.[128] 2,4-Dibromo resorcinol

119 was prepared according to literature procedure.[129] The activated tosylate 117 was reacted

with 2,4-dibromoresorcinol 119 using K2CO3 in DMF and gave 120 in 76% yield (Scheme 52).

Compound 120 was purified by silica gel column chromatography and the purity of meta-

monomer 120 was confirmed by high resolution 1H and 13C NMR spectroscopy and micro

analysis.

72 %

OHHO OHHO

Br Br

OO

Br Br

Br2

CHCl3

OO

OOH

OO

OO

SO O

25 117

K2CO3

DMF76 %

117

OO

O

O

O

O

TsCl, NaOH

THF86 %

118 119 120

Scheme 52: Synthesis of meta-dibromo monomer 120.

3.4.4. Suzuki polycondensation Polymer 121 was obtained by SPC of monomers 120 and 45 according to the synthetic

procedure described in Chapter 2.2.5. A series of optimization experiments were carried out

between the two monomers in order to achieve a precise 1:1 stoichiometry, and thereby to obtain

high molecular weight materials.


87

OO

Br Br

OO

O

O

O

O

120

BBO

OO

O+

OO

OO

O

O

O

O

45 121

Pd[P(p-tolyl)3]3NaHCO3

THF/H2O~ 90%

Scheme 53: Synthesis of poly(meta-phenylene) 121.

The purity of polymer 121 was determined by high resolution 1H and 13C NMR spectroscopy

and micro analysis. All NMR peaks supported the molecular constitution of the product,

indicating that a structurally defined polymer was obtained. Yields and molecular weights

determined by GPC calibrated vs polystyrene standards are summarized in Table 16. Molecular

weights obtained are relatively low after several experimentations. The highest degree of

polymerization for polymer 121 (entry 3, Table 4) was Pn = 13 (Mn = 6.1 kg/mol) and Pw= 24

(Mw = 11.6 kg/mol).

Table 16: Conditions for polymerization of monomer 120 using Pd[P(p-tolyl)3]3 as catalyst


Entry Mn

[kg/mol]

Pn

Mw

[kg/mol]

Pw

PDb

Yield

[%] 1 5.3 11 8.6 18 1.6 96

2 6.1 13 11.6 24 1.9 91

3 4.8 10 9.2 19 1.9 86

4 6.3 13 11.3 23 1.8 93


b. PD = Mw/Mn


88

3.5. Determination of trace elements by inductively coupled plasma mass

spectrometry (ICP-MS) and laser ablation-ICP-MS

As described in Chapter 2.6.2., for determining low amounts of Pd and for the determination

of „bound“ Pd, the spectrophotometric method was not sufficient. Therefore, in the case of

poly(meta-phenylene)s, ICP-MS and laser ablation-ICP-MS techniques were applied as sensitive

methods to determine quantitatively trace amounts of the relevant elements. This work was done

in collaboration with Prof. Detlef Günther, ETH Zürich. The polymer samples were digested and

analyzed by solution nebulization-ICP-MS. A second part of the sample was pressed into a pellet

and used as external calibration material for the direct solid trace element determination.

The elements P, Pd, B, Na were analyzed using C as internal standard. However, the samples

were tested for more than 40 other isotopes, although all of those were below the typical limits of

detection. Except for Na, where low concentrations and high standard deviations were obtained,

element concentrations were determined with an RSD of approx 10-15%. Br, which was also of

interest within the samples, was not quantitatively determined due to the lack of an external

standard. However, to give a relative information, cps and the ratio of Br to P are given in Table

17 and 18. All trace elements are reported with standard deviation values.



Polymer P

ppm

Pd

ppm

B

ppm

Na

ppm

Br/P

(CPS)

101 1478 ± 70 683 ± 74 88±10.6 118±52 90694±11493

103 1240 ± 24 896 ± 105 2.2± 2.8 9.8±3.2 87301±6428

109 1655 ± 129 157 ± 18 33.6±6 65.1±29 130833±8131

Table 18 shows the quantitative trace element analysis of polymer 101 (entry 6, Table 11)

with three different samples by the laser ablation-ICP-MS technique. Entry 1 in Table 18 refers to

polymer 101 as obtained. Entry 2 refers to purified polymer 101, obtained by treating the

polymer with N,N-diethyl-2-phenylhydrazinecarbothioamide ligand to remove residual Pd traces.

Entry 3 is a sample that was subjected to four consecutive precipitations in methanol in order to


89

remove colored impurities. A comparison of entry 1 with entry 2 clearly shows that there was an

improvement in the removal of Pd as well as P. After precipitation (entry 3), the Pd content could

be decreased down to 455 ppm but somehow there was an increase in the phosphorous content

(1478 ppm), possibly caused by external contamination.



Entry PMP

(101)

P

ppm

Pd

ppm

B

ppm

Na

ppm

Br/P

(CPS)

1 Polymer as

obtained 2170± 473 7535 ± 1257 9.4±4.9 363±160 38862 ±1460

2 After ligand

treatment 964 ± 573 1049 ± 647 1.6±0.4 44 ± 18 3441± 77

3 precipitation 1478 ± 49 455 ± 15 7 ± 4.8 49 ± 14 4171 ±1284

3.6. Determination of plausible end groups in the PMPs synthesized For SCC as well as SPC, reports appeared in the literature that shed light on some side

reactions such as homocoupling, deboronification, dehalogenation and ligand scrambling.[33, 130-

131] Amongst these reactions, ligand scrambling seems to be the most relevant side reaction.

Ligand scrambling is the aryl–aryl exchange between aryls at the Pd center and the phosphorus of

the ligand. In SCC, some researchers prefer to use the boronic acid component in a slight excess

due to slow deboronification.[130] However, in SPC, the AA- and BB-type monomer’s 1:1

stoichiometry is strictly required.

Jayakannan et al.[132] reported the end group analysis of regioregular poly(3-octyl-thiophene)s.

They reported hydrolytic deboronation and deiodination side reactions. They also determined

aryl-aryl exchange reactions and produced phenyl- and o-tolyl -capped chains. Herein, we

investigated the plausible end groups of polymer 109 by the matrix-assisted laser

desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) technique.


90

Figure 34: MALDI-TOF mass spectrum (TCNQ matrix) of a low molar mass fraction of

polymer 109 in reflector mode.

The low molecular weight polymer 109 (entry 5, Table 13) was subjected to MALDI-TOF MS

for the end group analysis. The MALDI-TOF mass spectrum of polymer 109 in the TCNQ matrix

showed a number of characteristic signals with a regular isotope pattern (Figure 34). One of the

blocks of the regular isotope pattern was amplified, as shown in Figure 35. The difference

between the two blocks was roughly 264 a.u.’s which was found to be acceptable with the mass

of polymer 109 (repeat unit: 266 a.u). The MALDI-TOF mass spectrum of polymer 109 in the

TCNQ matrix showed four characteristic signals in each block. Considering the above mentioned

side reactions and other possible end groups, four end groups for polymer 109 were assigned as

shown in Scheme 54.

Figure 35: MALDI-TOF mass spectrum of polymer 109; expanded and amplified isotope pattern

of the MALDI-TOF mass signal between m/z = 2940 and m/z = 3085.


91

The exact molecular weight of an 11mer of polymer 109 should give a signal at m/z = 2926.

The MALDI-TOF mass spectrum of polymer 109 in the TCNQ matrix for the 11mer showed

signals at m/z = 2971.73, 2984.81, 3047.76 and 3056.92 which corresponds to the end group

patterns of 122, 123, 124 and 125, as shown in Scheme 54. The observed monoisotopic mass of

the polymer 109 did not match exactly the calculated mass as shown in Table 19. This indicated

that the results of the end group analysis reported have to be considered as being preliminary.

Further, careful investigations have to be made by changing the substitution pattern, the matrix,

the number of independent polymer samples etc. Also chemical modifications of end groups have

to be taken into consideration. Table 19: Observed and calculated monoisotopic masses of the polymer 109.

Entry Elemental composition Mcala Mobs

b

1 C209H245O13B 2973.86 2971.73

2 C209H245O14B 2988.85 2984.81

3 C215H249O13B 3051.77 3047.76

4 C212H250O15B2 3057.89 3056.92 aCalculated value. bObserved value.

(HO)2B

H

OC6H13

H

OC6H13

(HO)2B B

B(OH)2

OC6H13O

O

(HO)2B

OH

OC6H13

122 123

124 125

11

11

11

11

Scheme 54: Plausible end groups on the basis of observed m/z values for polymer 109.


3.7.1. UV/VIS absorption properties of polymer 101 All PMPs prepared showed blue emitting fluorescence. Polymer 101 was selected for

spectroscopic analysis because this polymer yielded a high molecular weight material and gave


92

outstanding mechanical properties amongst all PMPs. Polymer 101 was investigated by UV/VIS

and fluorescence spectroscopy. The UV/VIS absorption spectrum of polymer 101 was recorded

in two different solvents, dichloromethane and toluene. In both solvents, the absorption

maximum was at 293 nm (Figure 36a and 36b, Table 20). In the case of toluene, measurements

below 280 nm were not possible due to strong light absorption by the solvent. For both solvents,

the absorbance of polymer 101 at λmax increased linearly with polymer concentration (Figure 36c

and 36d).

250 300 350 400 450 5000.0

0.2

0.4

0.6

0.8

1.0

1.2a

16.38 mg/L10.54 mg/L8.72 mg/ L6.04 mg/L3.38 mg/L1.31 mg/L

Polymer 101 in CH2Cl2 at 25 °C

OD

(I =

1 c

m)

wavelength, nm

300 350 400 450 5000.0

0.2

0.4

0.6

0.8

1.0

1.2b

OD

(I =

1 c

m)

wavelength, nm

16.00 mg/L10.70 mg/L7.37 mg/L4.30 mg/L2.04 mg/L1.13 mg/L


0 2 4 6 8 10 12 14 16 18 200.0

0.2

0.4

0.6

0.8

1.0

1.2 c Polymer 101in CH2Cl2, 25 °C

OD

(l =

1 c

m)

RMK-meta-OCH2C6H13 conc. mg/L

λmax293.6 nm

0 2 4 6 8 10 12 14 16 18 20

0.0

0.2

0.4

0.6

0.8

1.0

1.2 d Polymer 101in toluene, 25 °C

OD

(l =

1 c

m)

RMK-meta-CH2OC6H13 conc. mg/L

λmax

292.9 nm

Figure 36: UV/VIS spectrum of polymer 101 dissolved in dichloromethane (a) or toluene (b)

measured of dilute polymer concentrations. T = 25 °C. The absorbance at λmax vs concentra-tion

is ploted in c and d.


93

Table 20: Absorption maximum of polymer 101 determined in dichloromethane and toluene.

Concentration range: ca. 1.1 – 16 mg/L (ca. 5 – 62 μM constitutional repeating units, M = 266

g/mol).

Wavelength Dichloromethane Toluene

λmax (nm)

293.5 ± 0.1

293.6 ± 0.3

Compared with PPP 56, the absorption maximum of PMP 101 is at lower wavelength which is

mostly due to the extra electron delocalization from the oxygen lone pairs in the case of polymer

56.

3.7.2. Fluorescence spectroscopy

The fluorescence emission and excitation spectra of polymer 101 dissolved in

dichloromethane and in toluene were measured. In both solvents, there were two emission

maxima at 358 nm and 375 nm with shoulders at 340 nm, 390 nm and 420 nm (Figure 37). The

position of the emission maxima was independent on the excitation wavelength (Figure 37a).

350 400 450 500 550 6000

200000

400000

600000

800000

1000000

1200000





excitation at 287 nmexcitation at 284 nmre

lativ

e flu

ores

cenc

e in

tens

ity

wavelength, nm


1.13 mg/L


a

350 400 450 500 550 6000

100000

200000

300000

400000

500000

600000

rela

tive

fluor

esce

nce

inte

nsity

wavelength, nm


1.13 mg/L b


Figure 37: Emission spectrum of polymer 101 in dichloromethane (a) and toluene (b). In (a) the

excitation wavelength (λex) was between 281 nm and 299 nm. In (b) λex was 293 nm.

UV/VIS and fluorescence measurements indicated that polymer 101 is a stiff polymer. The

chemical nature of the solvent had little influence on the fluorescence properties. Two adjacent

benzene rings are likely to be„twisted“, like in the case of biphenyl. There was no extensive

conjugation along the polymer backbone.


94

3.8. IR Spectroscopy In the case of intrinsically insoluble PPP, IR spectroscopy has been conventionally the typical

tool for structural analysis.[133-135] For substituted soluble PPPs, other methods are available e.g.

NMR spectroscopy. Yamamoto and co-workers reported the IR spectrum of the product obtained

from the polycondensation reaction between para-dibromobenzene and meta-

dibromobenzene.[136]

The IR spectrum of polymer 101 was recorded before and after processing the polymeric

material. Both spectra showed the absorption of the aliphatic and aromatic C-H stretching

oscillations between 3100 and 2800 cm-1. The aromatic ring vibrations and the deformation

vibrations of the side chains appeared in the finger-print region between 1610 and 1300 cm-1. The

strong band at 1205 cm-1 is attributed to an asymmetric COC-vibration. While for alkyl-

substituted PMPs, the out-of-plane vibration of the aromatic hydrogen showed a strong

absorption at 890 cm-1. Figure 38 and 39 show a direct comparison of the IR-spectrum of

polymer 101 measured before and after melt-compression of the polymeric material. The heat-

pressure treatment did not lead to changes in IR spectrum. However, the color of the polymer 101

was changed from white (before processing) to brown (after processing). This color change upon

heating upto 180 °C was possibly due to the presence of residual catalyst.

Figure 38: IR spectrum of polymer 101 before melt-compression with KBr.


95

Figure 39: IR spectrum of polymer 101 after melt-compression as a film.

3.9. Thermal, WAXS and mechanical properties of polymer 101 In the present work, the material’s characteristic properties of one selected member of the

PMP family (polymer 101) are described in detail. This polymer was found to exhibit a highly

useful combination of properties, including convenient processability, a high glass transition

temperature, (Tg) and outstanding toughness, i.e. capability to absorb mechanical energy -

rivalling that of high-performance polycarbonates (PC), but with improved resistance against

environmental stress-cracking, a faiblesse of the latter engineering polymer.[137, 138]

3.9.1. Thermal properties

3.9.1.1. Thermogravimetric analysis (TGA)

TGA is a testing procedure in which changes in weight of a specimen are recorded as the

specimen is heated in air or in a controlled atmosphere such as nitrogen. It is commonly

employed in research and testing to determine characteristics of materials such as polymers to

determine degradation temperatures, absorbed moisture content of materials and the level of

inorganic and organic components in materials. TGA of the various polymer fractions (polymer


96

101, Table 12) were conducted in air at a rate of 2 °C/min. The thermograms showed that

polymer 101 commenced to display a rapid weight loss at temperatures exceeding about 310 °C.

We must note, however, that the polymer 101 featured discoloration upon heating at temperatures

exceeding 180 °C, possibly due to the presence residual catalyst.

3.9.1.2. Differential scanning calorimetry (DSC)

DSC is a thermo analytical technique in which the difference in the amount of heat required to

increase the temperature of a sample and reference are measured as a function of temperature.

Both the sample and reference are maintained at the same temperature throughout the

experiment. In the present work, the DSC analysis of once-molten polymer samples (polymer

101, Table 12) is presented in Figure 40. The data indicate a relatively pronounced, typical

molar-mass dependent[139] glass temperature, Tg, in the elevated range from 149 to 166 °C for

polymer 101 of Mn of 14×103 to 194×103 g/mol. These values significantly surpass those of

traditional bulk amorphous polymers, such as atactic polystyrene (a-PS) and poly(methyl

methacrylate) (PMMA), which are found at about 100 °C, and compare favourably with that of

high-performance polycarbonates of ~150 °C.[140]

Figure 40: Differential scanning calorimetric (DSC) thermograms of once-molten polymer 101

(fractions 1-3, Table 12) revealing pronounced glass transition temperatures.


97

3.9.2. X-ray scattering

Wide-angle X-ray scattering (WAXS) is an X-ray diffraction technique that is often used to

determine the crystalline structure of polymers. Two different WAXS analysis of polymer 101

(fraction 1, Table 12) were carried out, first as a melt-compression molded film of polymer 101

and then the same polymer but solidified by slow evaporation, see Figure 41.

a)

b)

Figure 41: Top: a) Wide-angle X-ray scattering (WAXS) pattern of a melt-compression molded

film of PMP 101 (fraction 1, Table 12) revealing its largely amorphous nature; b) WAXS pattern

of the same polymer, but solidified by slow evaporation of DMF from a 1 % solution, indicative

of crystalline order. Reflections were found corresponding to lattice spacings of 3.9, 7.6 and 9.1

Å. Bottom: X-ray intensity vs scattering vector q diagrams of samples in a) and b).


98

WAXS indicated that the melt-compression-molded polymer sample of PMP was largely

amorphous (Figure 41 a, top). It should be noted, however, that – due to the particular chemical

route employed – the present PMP 101 is a regioregular macromolecule that under the

appropriate experimental conditions (e.g. slow cooling, slow precipitation from solution or in

flow fields) should be able to form an ordered phase, similar to PC.[141] Solidification of the

polymers from dichloromethane by evaporation of the solvent at room temperature yielded

slightly birefringent films, indeed indicative of the presence of crystalline order, consistent with

their WAXS patterns (Figure 41 b, top). Standard analysis[142] of the radially integrated (0.3-3.5 Å-1)

patterns yielded a degree of crystallinitiy of approximately 5% (Figure 41, bottom). DSC analysis of

such materials exhibited endothermic transitions in the range from 185-210 °C, which was

attributed to the melting of crystalline polymer 101.

3.9.3. Mechanical properties

The mechanical properties are considered as the most important of all the physical and

chemical properties of high polymers for most applications.[143, 144] The mechanical behavior can

be modified not only by the chemical composition but particularly by numerous structural factors

such as, a) molecular weight, b) cross-linking & branching, c) crystallinity, d) molecular

orientation and e) blending. In addition to the structural and molecular factors, following

environmental variables are also important in determining the mechanical behavior of polymers:

i) temperature, ii) time, frequency, rate of stressing or straining, iii) stress and strain amplitude,

iv) type of deformation (shear, tensile, biaxial etc) and v) heat treatments.

In the present work, the mechanical properties of one selected member of PMP family

(polymer 101) were investigated in detail and compared directly with a-PS, PMMA and PC. Due

to their relatively low molar masses, melt-compression-molded films of polymer 101 (fractions 2

and 3, Table 12) displayed such brittleness that their mechanical properties could not be tested in

a reliable manner. In contrast, films of the high molar mass fraction 1 (Table 12) were flexible

and tough and could be deformed well past the yield point. In Figure 42, results are presented of

room-temperature tensile deformation tests of these PMP films (thickness ~150 μm). For

comparison, stress-strain curves are presented also of melt-compression molded films of similar

thickness of common a-PS, PMMA and PC.


99

The PMP 101 films, albeit of a somewhat lower stiffness, featured a nominal stress at break

similar to the above polymers, but, remarkably, exhibited a macroscopic elongation at break that

surpasses those of the highly brittle former two bulk polymers, and approaches that of PC, which

is reputed for its toughness (Table 21, Figure 42).

Figure 42: Stress-strain curves, recorded at room temperature of melt-compression molded films

of polymer 101 (fraction 1, Table 12). For reference purposes, corresponding curves of a-PS,

PMMA and PC are also shown, illustrating the excellent mechanical properties of the new

polyarylene (Table 21).

Table 21: Direct comparison of polymer 101 with corresponding curves of a-PS, PMMA and PC.

Polymer Young’s

Modulus GPa

Yield Stress

MPa

Tensile

Strength MPa

Strain at

Break %

Strain Energy

MJ/m3

PMP 101 1.0 57.7 75.0 122 71.8

PC 2.3 63.8 78.3 160 96.3

PMMA 3.2 87.3 87.3 7 4.9

a-PS 2.4 - 44.1 2 0.5


100

An undesirable feature of amorphous polymers is their tendency to become increasingly

brittle in the course of time.[145-147] The latter phenomenon – commonly referred to as “aging” –

typically manifests itself in a significantly increased yield stress and reduced elongation at

break.[148-150] Gratifyingly, accelerated aging studies revealed that storage of polymer 101,

fraction 1 films at 110 °C for periods of 48 hrs and then up to 1 month caused only a gradual

increase in yield strength of 28% at 5.4 MPa/decade, accompanied with only a modest reduction

of the elongation at break of 15% (Figure 43). The latter values compare favourably with those of

PC exposed to similar experimental conditions.[149, 150]

Figure 43: Accelerated ageing experiment of polymer 101, a) control stress-strain curve of

polymer 101; b) polymer sample annealed for 48 hrs at 110 °C and c) polymer sample annealed

for 1 month at 110 °C.

Another major drawback of most glassy polymers is the sensitivity of their mechanical

properties to specific solvents, generally referred to as environmental stress-cracking.[137, 138]

Most interestingly, in tensile tests carried out with polymer 101 immersed in methanol (Figure

44a) displayed a superior resistance to this unwanted feature when compared to PC (Figure 44b).

The latter beneficial property may be of relevance in, for instance, medical applications, where

sterilization at elevated temperatures and contact resistance against alcohols is a critical

requirement.


101

Figure 44: Stress-strain curves of a) polymer 101 and b) polycarbonate samples recorded while

immersed in methanol, showing the superior resistance of polymer 101 against environmental

stress cracking induced by methanol.

A series of PMPs having different alkyl or oligo ethyleneoxy glycol chains were successfully

synthesized. The chemical structure of the polymer 101 was studied systematically and thus, may

serve as a model for a new family of high-performance materials.[151] From a synthetic point of

view; it can readily be envisioned to widely vary both the structure of the backbone and the

lateral substituent(s), as well as to create random copolymers. Furthermore, PMPs could be

designed to fold up into helices, whose length is determined by the degree of polymerization and

whose pore diameter is defined by the distance between consecutive meta units in the backbone.

Specifically, in regard to helix length, such polymers are likely to be superior to their extensively

explored congeners, the monodisperse foldamers.[152]

Chapter 4 Investigation on SPC of tetra substituted monomers

102

4. Investigation on SPC of tetra substituted monomers with aryl

boronic acid esters In the beginning of this work, SPC was used for the synthesis of linear as well as branched

PPPs starting from disubstituted dihalo monomers. Herein, we investigated the synthesis of tetra-

substituted dibromo monomers and attempts were made for the polymerization reaction using

freshly prepared Pd-catalyst.

4.1. Synthesis of polymers 127, 128 and 131. 4.1.1. Synthesis of monomers 126 and 130

Defunctionalization of organic functional groups is an equally desirable achievement as

compared to functionalization. The carbonyl group can be defunctionalized to a methylene group

by Clemensen[153] or Wolff-Kishner reduction,[154] both of which require very drastic reaction

conditions. Chandrasekhar et al.[155] reported that, the polymethylhydrosiloxane-tris

(pentafluorophenyl)borane [(PMHS)-B(C6F5)3] combination is a versatile carbonyl defunct-

tionalization system under mild and rapid conditions. Several aromatic as well as aliphatic

carbonyl compounds were effectively reduced to give the corresponding alkanes in high yields.

1,3-Bis(4-bromophenyl)-2-propanone 125 was prepared according to a literature procedure.[156]

Br

HOO Br

DCC

DMAPCH2Cl268 %

PMSE

B(C6F5)389%

BrBr BrO

Br

BrO

OPMSE

91%

124 125 126

129 130

Br

BrB(C6F5)3

Scheme 55: Synthesis of dibromo monomers 126 and 130.


103

The carbonyl compound 125 was effectively reduced to the corresponding dibromo monomer

126 with high yield. The carbonyl compound 129 was prepared on multigram scale following a

reported protocol.[157] Dibromo monomer 130 was synthesized using the same protocol with 91%

yield as shown in Scheme 55.

Scheme 56 shows the mechanistic pathway for the conversion of the carbonyl functionality

into a methylene group. Chandrasekhar et al.[155] proposed that complex C, which is formed from

B(C6F5)3 A and PMHS B, is responsible for the reduction of the carbonyl functionality.[158]

Complex C would react with carbonyl group D to form E which would produce the reaction

product, hydrocarbon F, and silyl ether G. The reductive elimination of product F reproduces the

species A to continue the catalytic cycle as shown in Scheme 56. Coordination of carbonyl

oxygen to boron for facile hydride transfer is also expected. Parks and Piers reported that Ph3SiH

and Et3SiH also operate in a more or less similar pathway; the intermediate E can be isolated if 1

equiv of Ph3SiH is used.[159] However, in the case of PMHS, even though 1 equiv of reagent was

used, the intermediate E could not be isolated and hydrocarbon conversion was observed within

5-20 min. This clearly indicates that PMHS is a powerful reducing agent in the presence of

B(C6F5)3. The carbonyl compounds 125 and 129 were converted into corresponding alkanes 126

and 130 within 10 min.

B(C6F5)3

Si OH

CH3

Si H B(C6F5)3

R R1

O

n

R R1

OH Si

Si H B(C6F5)3

Si O Si

+R R1

HH

A B

C

CD

E

F

G

Scheme 56: Postulated reaction mechanism for the conversion of a C=O group into a -CH2-

group as described by Chandrasekhar et al.[155]


104


Polymers 127 and 128 were obtained from SPC of monomer 126 with aryl boronic acid esters

45 and 48 respectively in THF/H2O using freshly prepared Pd[P(p-tolyl)3]3 as catalyst precursor

and NaHCO3 as base. Polymer 131 was prepared from SPC of monomers 130 and 45 with the

same protocol as shown in Scheme 57. To meet the required exact 1:1 stoichiometry, a series of


the molar proportions were slightly modified around the presumed matching point.

Br Br

Br

Br

126

130

+ BBO

O O

OR

R

BBO

O O

O+

R

R

45 : R = H

48 : R = C6H13

127 : R = H

128 : R = C6H13

45 131

NaHCO3

THF/H2O~95 %

n

n97 %

NaHCO3

THF/H2O

Pd

Pd

Scheme 57: Synthesis of polymers 127, 128 and 131.

During the polymerization reaction of monomers 126 and 130 with aryl boronic acid esters 45,

a white precipitate was formed in the reaction mixture. The white material was completely

insoluble in any organic solvent. The soluble part was used for the characterization of polymers

127 and 131 but the molecular weight determined by GPC against polystyrene standards showed

only oligomers with 10-15% yield. For the synthesis of soluble polymers, SPC of monomer 126

was carried out with aryl boronic acid ester 48 using established SPC reaction conditions. The

polymer 128 was completely soluble in chloroform, CH2Cl2 and THF and partially soluble in

toluene. The molecular weights of polymer 128 determined by GPC against polystyrene

standards are summarized in Table 22. Polymer yields are high and usually beyond 90%. The

highest degree of polymerization for polymer 128 (entry 1, Table 21) was Pn = 15 (Mn = 6.9


105

kg/mol) and Pw= 47 (Mw = 21.4 kg/mol). The purity of polymer 128 was confirmed by high

resolution NMR spectroscopy and micro analysis.

Table 22: Conditions for polymerization of monomer 126 using Pd[P(p-tolyl)3]3 as catalyst


Entry Mn

[kg/mol]

Pn

Mw

[kg/mol]

Pw

PDb

Yield

[%]

1 6.9 15 21.4 47 3.0 92

2 5.4 12 21.5 47 3.9 89


b. PD = Mw/Mn

4.2. Synthesis of PPPs using rigid monomers

4.2.1. Synthesis of rigid monomers

Condensation reaction of 132 with commercially available benzil 133 in ethanolic potassium

hydroxide gave 2,5-bis(p-bromopheny1)-3,4-diphenylcyclopentadienone 134 in 74% yield. The

Diels-Alder reaction of 134 with diphenylacetylene at 305 °C gave the rigid dibromo monomer

137 in high yield as shown in Scheme 58. This reaction was easily monitored visually because of

the loss of the dark purple color of 134. The small amounts of colored impurities were removed

by repeated recrystallization.

Br Br

132

+OO

O

EtOH

KOH

74 %

+ reflux, 3d83 %

Br Br

ClCl

133 134

134 136 137

O BrBr

O BrBr

Scheme 58: Synthesis of rigid monomers 134 and 137.


106


SPC of dibromo monomers 134 and 137 with aryl diboronic acid esters 45 were carried out

using established SPC reaction conditions. A series of optimization experiments were carried out

according to synthetic procedure described in Chapter 2.2.5. During the polymerization reactions,

a white precipitate was formed in the reaction mixture. The white material was completely

insoluble in any organic solvents. High resolution MALDI showed the presence of oligomeric

materials only.

BBO

O O

O NaHCO3

THF/H2O94 %

PdO BrBr

Br Br

134

137

+

+ BBO

O O

ONaHCO3

THF/H2O98 %

Pd

n

45

45

135

138

O n

Scheme 59: Synthesis of rigid polymers 135 and 138.

4.3. Synthesis of PPPs using tetra-substituted monomers

4.3.1. Synthesis of tetra substituted dibromo monomer 141

Tobe and co-workers reported the synthesis of tetraiododichlorobenzene from

dichlorobenzene by periodonation.[160] Furthermore, the tetraiodo derivative was reacted with

phenylacetylene under Sonogashira coupling conditions to afford tetrakis(phenylethynyl)

benzene in 44% isolated yield.[160] The same synthetic strategy was applied for the preparation of

D2h symmetric (3,6-dibromobenzene-1,2,4,5-tetrayl)tetrakis(ethyne-2,1-diyl)tetrabenzene 141.

The synthesis of the designed tetra substituted dibromo monomer 141 was started from the

commercially available 1,4-dibromobenzene 139. Symmetrical 1,4-dibromo-2,3,5,6-tetra-


107

iodobenzene 140 was prepared from 1,4-dibromobenzene by periodonation with 78% yield. The

product was purified by repeated recrystallization and the purity of compound 140 was confirmed

by correct values from micro analysis (see Experimental Section). Compound 140 was insoluble

in most of the organic solvents at room temperature therefore a 13C NMR spectrum could not be

recorded. The classical Sonogashira coupling reaction was carried out on the symmetrical 1,4-

dibromo-2,3,5,6-tetraiodobenzene 140 and phenyl acetylene using freshly prepared Pd(PPh3)4 as

catalyst precursor. Unsymmetrical 142 and 143 side products instead of symmetrical dibromo

compound 141 were obtained. Formation of these unsymmetrical side products indicates that the

phenyl group was introduced from the catalyst precursor and not from starting compounds. This

shows that ligand scrambling is a potential side reaction in these types of transition metal

catalyzed coupling reactions.

Br Br

I I

IIPd(PPh3)4

DMF

Di-isopropyl amineCuI

Br Br Br Br

Br BrBr BrH2SO4

H5IO6

I274 %

139 140 141

142 143

Scheme 60: Attempts for the synthesis of symmetrical dibromo monomer 141.

4.3.2. Synthesis of tetra substituted dibromo monomer 145

Hart and co-workers reported the synthesis of tetraphenylbenzene derivatives using the

Grignard reaction.[161] In the present work, the tetraaryl dibromomonomer 145 was synthesized

using the Suzuki-Miyaura cross coupling reaction. SCC reaction of symmetrical compound 140


108

and phenyl boronic acid using freshly prepared Pd(PPh3)4 as catalyst precursor gave dibromo

monomer 145 as shown in Scheme 61. Compound 145 was purified by silica gel column

chromatography using hexane/ethyl acetate as eluent.

Br Br

I I

II

(HO)2B Br BrPd(PPh3)4

K2CO3

DMF37 %

+

140 144 145

Scheme 61: Synthesis of tetraaryl dibromo monomer 145.


Scheme 62 depicts the synthetic route to the rigid polymer 146. Two SPC reactions were

performed with monomers 145 and 45, by slightly changing the mole ratio in order to achieve a

1:1 stoichiometry. For each experiment, about 500 mg of monomer 145 was used. During the

polymerization reaction, a white precipitate was formed. The white material was completely

insoluble in any organic solvents.

Br Br B BO

O O

O

n+

145

NaHCO3

THF/H2O98 %

Pd

45 146

Scheme 62: Attempts for sterically demanding SPC of monomer 145.

4.3.4. Synthesis of a tetraalkyl substituted monomer

The 1,2,4,5-tetrahydroxybenzene 148 was easily prepared on a scale of several grams by Pd

catalyzed hydrogenation of dihydroxybenzoquinone 147 following a reported protocol.[162]

Jenneskens and co-workers reported the synthesis of dibromo monomer 150, first by alkylation of

tetrahydroxybenzene and then bromination of the aromatic ring.[163] In the present work, the

bromination of 148 first carried out and then, the alkoxy chains were attached via classical


109

Williamson etherification synthesis with high yields as shown in Scheme 63. The tetra substituted

dibromo monomer 150 was purified by silica gel column chromatography using hexane/ethyl

acetate as an eluent and further by recrystallization. The purity of the tetra-substituted monomer

150 was confirmed by high resolution 1H and 13C NMR spectroscopy and correct values from

micro-analysis.

OH

HO

O

O OH

HO

OH

HO OH

HO OH

HONaOH

C6H13Br

5 %Pd / C

H2

O

O O

O

BrBrBr2

acetic acidabs. ethanol84 %

86 %79 %

147 148 149

150

BrBr

Scheme 63: Synthesis of tetra substituted dibromo monomer 150.


SPC of the tetra substituted dibromomonomer 150 and 45 was carried out under established

SPC reaction conditions (Scheme 64). The product obtained was completely soluble in organic

solvents and only trimers to pentamers formed, no polymers.

O

O O

O

BrBr

150

O

O O

O

nBB

O

O O

O+

PdNaHCO3

THF/H2O96 %

151

45

Scheme 64: Attempts for the SPC reaction of the tetra substituted dibromo monomer 150.


110

The formation of polymers was hindered under the conditions used, most likely because the

monomers were too rigid. This concludes that SPC of tetra substituted monomers could not be

achieved successfully. In future work it may be worth to try SPC of tetra substituted monomers

with shorter alkyl chains.

Chapter 5 Experimental Section

111

5. Experimental section

5.1 General All commercially available substances were purchased from Acros, Merck, Fluka or Aldrich and

used without further purification. Solvents were purified and dried - if necessary - according to

standard methods.[164] All reactions involving air-sensitive compounds were carried out under

nitrogen using standard Schlenk techniques and dry, oxygen-free solvents. n-BuLi was used as a

1.6 M solution in hexane.

5.1.1. Preparative chromatographic Methods

Analytical TLC: All reactions were monitored on silica gel alumina sheets (Merck ‘‘Kieselgel 60’’, with

fluorescence indicator F254). For detection, UV-light of the wavelengths λ= 254 or λ= 366 nm

was used. Some of the compounds were visualized by putting the TLC plate into an iodine

chamber.

Column chromatography: The chromatography was run with Merck flash silica gel (230-400 mesh STM, grain size 40-60

pm), or Fluka aluminum oxide neutral (Typ 507 C, 0.05-0.15 mm). For all chromatographed

compounds the Rf value is given together with the eluting solvent in the TLC.

5.1.2. Product Analysis

Melting point: Instrument: Büchi SMP 510, uncorrected values.

NMR spectroscopy: Instruments: Bruker WH 270, Bruker AB 250, Bruker Avance 300, Bruker Avance 500, Bruker

Avance 700. The signals of non-deuterated solvents served as internal standard TMS (1H: CDCl3

δ = 7.26 ppm, CD2Cl2 δ = 5.32 ppm; CD3OH δ = 3.31 ppm; [D6]-DMSO δ = 2.50 ppm; 13C:

CDCl3 δ = 77.16 ppm, CD3OH δ = 49.00 ppm; [D6]-DMSO δ = 39.52 ppm). The deuterated

solvents were purchased from Merck and Deutero GmbH. All spectra were recorded at 20 °C.


112

Mass spectrometry: Instruments: Perkin-Elmer Varian Type MAT 771 and CH6 (EI), or Bruker reflex (MALDI-

TOF) respectively. The high resolution mass spectra were obtained according to the peak match

method (MAT 771).

MALDI-TOF mass spectrometry: Spectra were recorded with a Kratos MALDI 3 from Shimadzu. 3-Hydroxypicolinic acid (3-

HPA), DCTB-mix (trans-2-[3-(4-tert-Butylphenyl)-2-methylprop-2-enylidene]malononitrile,

TCNQ (7,7,8,8-tetracyanoquinodimethane) or Ditranol were used as matrices for MALDI-FT-

and MALDI-TOF-MS.

Inductively coupled plasma mass spectrometry: Samples were pressed into pellets (15 t) approx. 1 cm in diameter and 3 mm in height. The

samples were ablated using a 193 nm Compex 110i Excimer laser (GeoLas M, Lambda Physik,

Göttingen, Germany).[165] Each pellet was analyzed 5 times using a 80 μm crater, 10 Hz

repetition rate and a fluence of 15 J/cm2.

UV/VIS and Fluorescence spectroscopy:

Instruments: Perkin-Elmer Lambda 19 for UV/VIS measurements (pathlength: 1 cm) and Spex

Fluorolog 2 for fluorescence measurements (pathlength: 1 cm).

Elemental analysis: The elemental analyses were performed on a Perkin-Elmer EA 240 and Leco 900 instruments.

Analytical GPC: (I) GPC measurements in chloroform as the eluent were performed at room temperature at a flow

rate of 1.0 mL/min. The column set consisted of SDV columns, and the detectors used were UV

and RI. PS standards were used for calibration. Viscotek GPC-System was used, equipped with a

pump and a degasser (GPCmax VE2001, flow rate 1.0 mL/min), RI detector (302 TDA), and

three columns (2×PLGel Mix-C and 1×ViscoGEL GMHHRN 18055, 7.5×300 mm for each).

(II) Analyses in NMP+0.5 wt.-% LiBr were performed at 70 °C at a flow rate of 0.8 mL/min; 100

μL of 0.15 wt.-% polymer solutions were injected. The column set consisted of two 300 mm × 8

mm columns filled with a PSS-GRAM spherical polyester gel having an average particle size of


113

7 μm and a pore size of 102 and 103 A°, respectively. UV (λ= 270 nm), RI, and differential

viscosity (Viscotek H502B) detectors were used.

Preparative GPC: Preparative recycling GPC (Japan Analytical Industry Co. Ltd., LC 9101) equipped with a pump

(Hitachi L-7110, flow rate 3.5 mL/min), a degasser (GASTORR-702), a RI detector (Jai RI-7), a

UV detector (Jai UV-3702, λ = 254 nm), and two columns (Jaigel 2H and 2.5 H, 20 × 600 mm for

each) using chloroform as eluent at room temperature.

Thermal analysis Thermogravimetric analysis (TGA) was conducted in air at a scan rate of 10 °C/min with a

Mettler Toledo TGA/SDTA851e instrument.

Differential scanning calorimetry (DSC) was carried out with a Mettler Toledo DSC822e

instrument under N2 atmosphere at a scan rate of 10 °C/min. The sample weight was ca. 5 mg.

All samples were first heated to a temperature of 240 °C, then cooled down to room temperature

at a rate of 10 °C/min, prior to recording the glass transition temperatures reported here.

Mechanical properties Mechanical testing was performed at room temperature with an Instron tensile tester (model

4411).

Wide-angle X-ray scattering Standard transmission wide-angle X-ray scattering (WAXS) was carried out on polymer films

with an Xcalibur PX instrument (Oxford Diffraction) using MoKα-radiation (λ = 0.71 Å).

5.2. Syntheses The catalysts Pd(PPh3)4

[76] and Pd[P(p-tol)3]3[77]

were synthesized according to literature

procedures and stored in the glove-box. Compounds 23[58], 28[19], 34[62], 49[79], 57[59], 64[88],

75[89], 85[92], 102[118], 108[121], 112[126], 115[127], 117[128], 119[129], 125[156], 129[157] and 150[163]

were prepared according to literature procedures.


114

5.2.1. General Synthetic Procedures

Method A: General procedure for monoalkylation 2,5-Dibromohydroquinone (1.0 equiv) was dissolved in a solution of NaOH/KOH (1.0 equiv) in

dry ethanol at room temperature. The solution was warmed to 60 °C with constant stirring,

followed by the dropwise addition of alkyl bromide (1.0 equiv). After 10 h of stirring, the

reaction mixture was cooled and filtered, and the precipitate was washed with methanol. The

precipitate was identified as disubstituted phenol as a side product. The filtrate was concentrated,

distilled water was added, and the mixture was acidified with conc. HCl. The resulting precipitate

was collected by filtration, washed with water and dried over anhydrous MgSO4. After

evaporation of the solvent in vacuo, the crude material was purified by column chromatography.

Method B: General procedure for monoalkyl bromide To a degassed mixture of 2,5-dibromohydroquinone (1.0 equiv), NaOH (1.0 equiv) and dry

ethanol, alkylene dibromide (1.0 equiv) were added over 15 min. The reaction mixture was

degassed once more and refluxed for 12 h. The reaction mixture was cooled; the solvent was

removed under reduced pressure. The residue was dissolved in water and extracted with CH2Cl2.

After evaporation of the solvent, the crude product was purified by column chromatography.

Method C: Synthesis of ether using benzyl bromide and 1,3-bis(3,6,9-trioxadecanyl) glycerol To a suspension of KOtBu (1.1 equiv) in anhydrous THF was added dropwise a mixture of 1,3-

bis(3,6,9-trioxadecanyl) glycerol (1.1 equiv) in anhydrous THF. The reaction mixture was stirred

for 1 h and a solution of benzyl bromide (1.0 equiv) in anhydrous THF was added and stirring

continued overnight. The reaction mixture was quenched by adding water. The aqueous layer was

extracted with 3 × Et2O. The combined organic fractions were then washed with brine and dried

over anhydrous MgSO4. After filtration and evaporation of the solvent, the crude material was

purified by column chromatography.

Method D: General procedure for monomer synthesis 2,5-Dihalo-4-(dodecyloxy)phenol (1.0 equiv), 1,3-bis-{2-[2-(2-methoxy-ethoxy)-ethoxy]-

ethoxy}-propane-2-sulfonic acid methyl ester (1.0 equiv) and K2CO3 (1.2 equiv) were dissolved

in a minimum quantity of acetonitrile and the reaction mixture was refluxed for 24 h. After

cooling to room temperature, the solvent was removed with a rotary evaporator under reduced


115

pressure and the residue was mixed with water and extracted with CH2Cl2. The organic layer was

dried over anhydrous MgSO4. The solvent was removed and the compound purified by column

chromatography through silica gel.

Method E: Suzuki polycondensation The amphiphilic macromonomer (1.0 equiv), 1,4-di(1,3,2-dioxaborinan-2-yl)benzene (1.0 equiv)

and NaHCO3 (2.0 equiv) were dissolved in THF (25 mL) and water (10 mL). The two-layer

system was degassed three times by evacuating and ventilating with nitrogen for 10 min each.

The apparatus was opened under a nitrogen stream and freshly prepared Pd[P(p-tol)3]3 (0.6

mol%) was added. Degassing was repeated as mentioned before. The reaction mixture was then

refluxed for 4 d under nitrogen. After cooling to 20 °C, CH2Cl2 (approx. 100 mL) was added and

the mixture was stirred for 30 min. The organic layer was separated and dried over MgSO4. After

removal of the solvent, a transparent blue emitting film was formed on the glass wall with an

intense bluish tone. This film was dissolved in the minimum amount of CH2Cl2 (40 mL) and then

the polymer was precipitated by the addition of methanol (200 mL), filtered and washed with

methanol.

5.2.2. Synthesis of compounds of Chapter 2

2,5-Dibromo-4-(dodecyloxy)phenol (24) OC12H25

OHBr

Br

Synthesis method A (see 5.2.1): 2,5-Dibromohydroquinone 23 (15.00 g, 56 mmol), NaOH (3.42

g, 85.5 mmol), dry ethanol (560 mL), dodecyl bromide (13.89 g, 56 mmol) and conc. HCl (7.6

mL). The crude product was purified by column chromatography through silica gel (hexane/ethyl

acetate, 98:02).

Yield: 14.67 g (60%).

Rf = 0.44 (hexane/ethyl acetate, 98:02). 1H NMR (CDCl3, 250 MHz): δ = 0.91 (t, 3H, J = 7.0 Hz, –CH3), 1.24 (m, 18H, -CH2CH2CH2–),

1.9 (quin, 2H, J = 7.5 Hz, β-CH2-), 3.88 (t, 2H, α-CH2–), 4.88 (b, 1H, –OH), 6.97 (s, 1H,

aromatic- H), 7.29 (s, 1H, aromatic-H).


116

13C NMR (CDCl3, 63 MHz): δ =14.08, 22.67, 25.93, 29.10, 29.29, 29.33, 29.56, 29.64, 31.91,

70.46, 108.36, 112.58, 116.78, 120.30, 127.90, 146.83, 150.13.

MS (EI, 80 eV, 180 °C): m/z (%)= 436.22 (27.95) [M]+, 267.9 (100) [M-Br]+.

EA C18H28O2Br2 Calcd: C 49.56, H 6.47;

(436.22) Found: C 49.66, H 6.32.

2,5,8,11,15,18,21,24-Octaoxapentacosan-13-yl methanesulfonate (29)

O

O

OO

O

O

OO

OSO

OH3C

To a solution of 1,3-bis (3,6,9-trioxadecanyl) glycerol 28 (20 g, 52.08 mmol) in CH2Cl2 (200

mL), triethylamine (7.879 g, 78.12 mmol) was added and the reaction mixture was stirred at 0 °C

for 15 min, methane sulphonyl chloride (8.931g, 78.12 mmol) was added dropwise and the

reaction mixture was stirred overnight. The reaction mixture was diluted with CH2Cl2 (100 mL),

followed by water (100 mL). The aqueous phase was extracted with CH2Cl2 (3 × 50 mL) and the

combined organic fractions were washed with brine and then dried over anhydrous MgSO4. After

filtration and evaporation of the solvent, the crude viscous oil was used further without any

purification.

Yield: 23.34 g (97%). 1H NMR (CDCl3, 250 MHz): δ = 3.1 (s, 3H, CH3), 3.31 (s, 6H, OCH3), 3.70-3.41 (m, 28H,

OCH2), 4.74 (quin, 1H, OHCH). 13C NMR (CDCl3, 62.896 MHz): δ = 38.34, 52.47, 58.83, 70.29, 70.38, 70.43, 70.47, 70.73,

71.80, 80.35.

MS (EI, 80 eV, 200 °C): m/z (%) = 485.6 [M + Na]+, 463.2 (34.80) [M]+.

EA C18H38O11S Calcd: C 46.74, H 8.28;

(462) Found: C 46.45, H 8.17.


117

1,4-Dibromo-2-dodecyloxy-5-(2-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-1-{2-[2-(2-

methoxy-ethoxy)-ethoxy]-ethoxymethyl}-ethoxy)-benzene (30)

BrBr

OC12H25

O

OO

OO

OO

OO

Synthesis method D (see 5.2.1): Monoalkylated phenol 24 (20 g, 45.87 mmol), compound 29

(21.28 g, 45.87 mmol), K2CO3 (31.65 g, 229.35 mmol) and acetonitrile (600 mL). The crude

product was purified by column chromatography (CH2Cl2/CH3OH, 97:3) gave a colorless oil.

Yield: 24.0 g (65%).

Rf = 0.27 (CH2Cl2/CH3OH, 97:3). 1H NMR (CDCl3, 250 MHz): δ = 0.86 (t, 3H, J = 7.0 Hz, –CH3), 1.24 (m, 16H, –CH2CH2CH2–),

1.46 (m, 2H, J = 7.5 Hz, γ-CH2-), 1.77 (quin, 2H, J = 7.5 Hz, β-CH2-), 3.34 (s, 6H, –OCH3), 3.62

(m, 24H, OCH2CH2O-), 3.89 (t, 2H, α-CH2–), 4.35 (quin, 1H, –OHCH), 7.1 (s, 1H, aromatic-H),

7.46 (s, 1H, aromatic-H). 13C NMR (CDCl3, 63 MHz): δ = 14.05, 15.30, 22.63, 25.91, 29.06, 29.28, 29.51, 29.61, 31.88,

58.97, 70.18, 70.50, 70.56, 70.64, 70.79, 71.15, 71.93, 80.94, 112.74, 117.71, 122.82, 150.94.

MS (EI, 80 eV, 200 °C): m/z (%) = 803.1 (4.91) [M]+.

EA C35H62Br2O10 Calcd: C 52.11, H 7.47;

(802.67) Found: C 52.17, H 7.46.


118

Poly(5-dodecyloxy-2-(2-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-1-{2-[2-(2-methoxy-

ethoxy)-ethoxy]-ethoxymethyl}-ethoxy)-4,4’-biphenylene) (31)

OC12H25

O

OO

OO

OO

OO

n

Synthesis method E (see 5.2.1): Dibromomonomer 30 (0.499 g, 0.62 mmol), 1,4-di(1,3,2-

dioxaborinan-2-yl)benzene 45 (0.153 g, 0.62 mmol), NaHCO3 (1.0 g), TBAB (0.179 g, 0.625

mmol), THF (25 mL), water (10 mL) and Pd[P(p-tolyl)3]3 (3.8 mg, 0.6 mol%).

Yield: 0.413 g (92%). 1H NMR (CD2Cl2, 500 MHz): δ = 0.85 (broad, 3H, –CH3), 1.24 (broad, 18H, –CH2CH2CH2–),

1.72 (broad, 2H, OCH2CH2CH2–), 3.32 (broad, 6H, –OCH3), 3.58 (m, 24H), 3.97 (broad, 2H, –

OCH2CH2-), 4.40 (broad, 1H, –OHCH), 7.01 (broad, 1H, aromatic-H), 7.27 (broad, 1H,

aromatic-H), 7.67 (broad, 4H, aromatic-H). 13C NMR (CD2Cl2): δ = 14.80, 23.37, 26.84, 30.36, 32.60, 59.67, 70.13, 71.29, 71.66, 72.62,

79.52, 116.44, 120.31, 129.86, 131.11, 132.59, 137.48, 137.85, 150.16, 151.88.

EA (C41H68O10)n Calcd: C 68.30, H 9.51;

(720.48)n Found: C 67.76, H 9.16.

4-(Dodecyloxy)-2,5-diiodophenol (35)

II

OC12H25

HO Synthesis method A (see 5.2.1): 2,5-Diiodohydroquinone 34 (7.00 g, 19.34 mmol), KOH powder

(3.25 g, 58 mmol), dry ethanol (50 mL), dodecyl bromide (3.19 g, 19.34 mmol) and conc. HCl

(2.4 mL). The crude product was collected by filtration and recrystallized from hexane

(refrigeration).


119

Yield: 5.00 g (56%).

M. p. 48–50 °C. 1H NMR (CDCl3, 250 MHz): δ = 0.87 (t, 3H, J = 7.0 Hz, –CH3), 1.33 (m, 16H, –CH2–), 1.47 (m,

2H, γ-CH2–), 1.77 (quin, 2H, J = 7.5 Hz, β-CH2-), 3.73 (t, 2H, α-CH2–), 4.88 (b, 1H, –OH), 7.01

(s, 1H, aromatic-H), 7.41 (s, 1H, aromatic-H). 13C NMR (CDCl3, 63 MHz): δ = 14.1, 22.8, 29.4, 29.6, 29.7, 29.56, 29.64, 31.9, 68.0, 86.3, 87.0,

124.0, 124.7, 150.3, 150.7.

MS (EI, 80 eV, 70 °C): m/z = 530 (42.71) [M]+.

EA C18H28O2I2 Calcd: C 40.77, H 5.32;

(530.22) Found: C 40.14, H 4.81.

1-Dodecyloxy-2,5-diiodo-4-(2-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-1-{2-[2-(2-

methoxy-ethoxy)-ethoxy]-ethoxymethyl}-ethoxy)-benzene (36)

II

OC12H25

O

OO

OO

OO

OO

Synthesis method D (see 5.2.1): Monoalkylated phenol 35 (11.00 g, 20.75 mmol), activated

mesylate 29 (9.89 g, 20.75 mmol), K2CO3 (14.32 g, 103.7 mmol) and acetonitrile (300 mL). The

crude product was purified by column chromatography (CH2Cl2/CH3OH, 97:3) gave a colorless

oil.

Yield: 12.08 g (65%).

Rf = 0.29 (CH2Cl2/CH3OH, 98:02). 1H NMR (CDCl3, 700 MHz): δ = 0.86 (t, 3H, J = 7.0 Hz, –CH3), 1.24 (m, 18H, –CH2CH2CH2–),

1.46 (m, 2H, OCH2CH2CH2–), 1.77 (quin, 2H, J = 7.5 Hz, β-CH2-), 3.34 (s, 6H, –OCH3), 3.62

(m, 24H, OCH2CH2O-), 3.89 (t, 2H, α-CH2–), 4.35 (quin, 1H,–OHCH), 7.1 (s, 1H, aromatic-H),

7.46 (s, 1H, aromatic-H).


120

13C NMR (CDCl3, 63 MHz): δ = 14.03, 22.61, 25.88, 29.04, 29.24, 29.27, 29.50, 29.58, 31.85,

58.94, 70.16, 70.47, 70.54, 70.61, 70.79, 71.12, 71.91, 80.92, 111.08, 112.71, 117.68, 122.78,

149.74, 150.92.

MS (EI, 80 eV, 180 °C): m/z = 934.9 (4.13) [M + K]+, 919 (19.20) [M + Na]+,896.9 (7.59) [M]+,

770.3 [M - I]+.

EA C35H62O11I2 Calcd: C 46.88, H 6.97;

(896.67) Found: C 46.91, H 6.81.

Poly[5-dodecyloxy-2-(2-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-1-{2-[2-(2-methoxy-

ethoxy)-ethoxy]-ethoxymethyl}-ethoxy)-4,4’-biphenylene] (37)

OC12H25

O

OO

OO

OO

OO

n

Synthesis method E (see 5.2.1): Diiodomonomer 36 (0.499 g, 0.625 mmol), 1,4-di(1,3,2-

dioxaborinan-2-yl)benzene 45 (0.137 g, 0.56 mmol), TBAB (0.179 g, 0.625 mmol), NaHCO3 (1.0

g), THF (25 mL), water (10 mL) and Pd[P(p-tolyl)3]3 (3.8 mg, 0.6 mol%).

Yield: 0.429 g (96%). 1H NMR (CD2Cl2, 500 MHz): δ = 0.85 (broad, 3H, –CH3), 1.23 (broad, 18H, –CH2CH2CH2–),

1.75 (broad, 2H, –OCH2CH2CH2–), 3.32 (broad, 6H, –OCH3), 3.57 (broad, 24H), 3.98 (broad,

2H, –OCH2CH2), 4.4 (broad, 1H, –OHCH), 7.02 (broad, 1H, aromatic-H), 7.30 (broad, 1H,

aromatic-H), 7.67 (broad, 4H, aromatic-H). 13C NMR (CD2Cl2, 63.5 MHz): δ = 15.30, 23.87, 27.35, 30.87, 33.10, 60.17, 70.64, 71.80, 72.16,

73.12, 80.03, 116.95, 120.82, 130.27, 131.62, 133.10, 138.00, 138.35, 150.67, 152.39.

EA (C41H68O10)n Calcd: C 68.30, H 9.51;

(720.48)n Found: C 67.44, H 9.01.


121

1-Dodecyloxy-2,5-dibromo-4-[PEG monomethyl ether 750]-benzene (39) OC12H25

OBr

Br

O

18 Monoalkylated phenol 24 (8.98 g, 20.6 mmol), triphenylphosphine (6.24 g, 30.9 mmol) and PEG

750 monomethyl ether 38 (6.24 g, 30.9 mmol) were dissolved in dry THF (40 mL). DIAD (6.58

g, 32.5 mmol) in 10 mL of dry THF was added dropwise under exclusion of light. The mixture

was stirred for 1 d at room temperature, the solvent evaporated and the crude product purified by

flash column chromatography (CH2Cl2/CH3OH, 98:02).

Yield 15.2 g (60%) of a colorless, waxy solid.

Rf = 0.25 (CH2Cl2/CH3OH, 98:02). 1H NMR (CDCl3, 250 MHz): δ = 0.87 (t, 3H, J = 7.0 Hz, –CH3), 1.33 (m, 4H, –CH2–), 1.47 (m,

2H, γ-CH2–), 1.77 (quin, J = 7.5 Hz, 2H, β-CH2–), 3.30 (s, 3H, OCH3), 3.50 (m, 2H, –CH2O–),

3.62 (m, 60 H, –CH2O–), 3.73 (t, 2H, J = 5.5 Hz, α-OCH2–), 3.87 (m, 4H, α-CH2–), 4.07 (t, 2H, J

= 5.5 Hz, α-OCH2–), 7.01 (s, 1H, aromatic-H), 7.11 (s, 1H, aromatic-H). 13C NMR (CDCl3, 63 MHz): δ = 14.08, 22.67, 25.93, 29.10, 29.29, 29.33, 29.56, 29.64, 31.91,

70.46, 108.36, 112.58, 116.78, 120.30, 127.90, 146.83, 150.13.

MS (EI, 80 eV, 180 °C): m/z = 1246.5 [M]+, 1226.9 [M – CH3]+, 1184.2 [M – OCH2CH2OCH3]+,

1141.7 [M – O(CH2CH2)2OCH3]+.

Poly[5-dodecyl-2-(PEG monomethyl ether 750)-4,4’-biphenylene] (40) OC12H25

O

O18

n

Synthesis method E (see 5.2.1): Amphiphilic monomer 39 (1.003 g, 0.94 mmol), 1,4-di(1,3,2-

dioxaborinan-2-yl)benzene 45 (0.232 g, 0.94 mmol), NaHCO3 (2.0 g), TBAB (0.40 g, 0.94

mmol), THF (50 mL), water (20 mL) and Pd[P(p-tolyl)3]3 (8.6 mg, 0.9 mol%).

Yield: 0.412 g (91%).


122

1H NMR (CDCl3, 500 MHz): δ = 0.86 (broad, 3H, –CH3), 1.24 (broad, 14H, –CH2–), 1.42

(broad, 2H, γ-CH2–), 1.75 (broad, 2H, β-CH2–), 3.36 (broad, 3H, OCH3), 3.65 (m, 60H, –CH2O–

), 3.80 (broad, 2H, –CH2O–), 3.99 (broad, 2H, α-CH2, -CH2O–), 4.15 (broad, 2H, α-OCH2–),

7.07 (broad, 1H, aromatic-H), 7.12 (broad, 1H, aromatic-H), 7.65 (broad, 4H, aromatic-H). 13C NMR (CDCl3, 63.5 MHz): δ = 13.60, 13.98, 19.74, 22.56, 24.28, 26.05, 29.23, 29.54,

31.80, 58.87, 59.28, 69.80, 70.51, 71.89, 76.47, 76.98, 77.48, 116.24, 117.01, 129.01, 130.56,

136.87, 150.15, 150.85.

EA (C60H104O20)n Calcd: C 63.35, H 9.22;

(1137.474)n Found: C 62.97, H 9.53.

1,4-Dibromo-2-(bromomethyl)-5-dodecylbenzene (50) C12H25

Br

Br

Br

1-(Bromomethyl)-4-dodecylbenzene 49 (24.07 g, 70.9 mmol) was mixed with powdered iodine

(522 mg, 2.10 mmol). The waxy mixture was cooled to 0 °C and bromine (22 mL) was added

dropwise under exclusion of light. The mixture was stirred for 6 d at room temperature, diluted

with 200 mL CH2Cl2 and the dark solution was poured into an ice-cold aqueous NaOH to reduce

residual bromine. The yellow layer was separated and the aqueous layer was extracted 2 ×

CH2Cl2. The combined organic layers were dried over MgSO4. After evaporation of the solvent,

the crude product was purified by column chromatography through silica gel using hexane as

eluent to afford a colorless solid.

Yield: 34.52 g (98%).

Rf = 0.72 (hexane/ethyl acetate 10:1).

M. p. 47 °C. 1H NMR (CDCl3, 250 MHz): δ = 0.87 (t, J = 7.3 Hz, 3H, –CH3), 1.27 (m, 18H, –CH2CH2–), 1.58

(quin, 2H, J = 7.6 Hz, β-CH2), 2.66 (t, 2H, J = 7.6 Hz, α-CH2-), 4.50 (s, 2H, –CH2Br), 7.40 (s,

1H, aromatic-H), 7.31 (s, 1H, aromatic-H). 13C NMR (CDCl3, 63 MHz): δ = 14.10, 22.68, 29.35, 29.51, 29.60, 29.63, 31.92, 32.07, 35.74,

122.99, 123.39, 134.33, 134.79, 136.04, 144.64.

MS (EI, 80 eV, 120 °C): m/z (%)= 496 (6) [M] +, 419 (5) [M – CH2Br] +, 415 (5) [M– Br] +.


123

EA C19H29Br3 Calcd: C 45.90, H 5.88;

(497.15) Found: C 46.37, H 5.78.

1,4-Dibromo-2-dodecyl-5-(2-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-1-{2-[2-(2-methoxy-

ethoxy)-ethoxy]-ethoxymethyl}-ethoxymethyl)benzene (51)

C12H25

O

Br Br

OO

OO

OO

OO

Synthesis method C (see 5.2.1): KOtBu (3.65g, 32.5 mmol), 1,3-bis (3,6,9-trioxadecanyl)

glycerol 28 (8.35 g, 21.6 mmol), benzyl bromide 50 (10.77 g, 21.6 mmol) and THF (300 mL).

Chromatographic separation on silica gel (CH2Cl2/CH3OH, 98:02) afforded a colorless oil.

Yield: 13.27 g (78%).

Rf = 0.31 (CH2Cl2/CH3OH, 98:02). 1H NMR (CDCl3, 250 MHz): δ = 0.89 (t, 3H, J = 7.3 Hz, –CH3), 1.27 (m, 18H, –CH2–), 1.58

(quin, 2H, J = 7.6 Hz, β-CH2), 2.66 (t, 2H, J = 7.6 Hz, α-CH2-), 3.42 (s, 6H, OCH3), 3.59 (m,

28H), 3.64 (m, 1H, -OCH-), 4.60 (s, 2H, –CH2Br), 7.40 (s, 1H, aromatic-H), 7.61 (s, 1H,

aromatic-H). 13C NMR (CDCl3, 63 MHz): δ =14.07, 22.60, 29.25, 29.31, 29.47, 29.56, 29.70, 31.84, 35.60,

58.91, 70.48, 70.54, 70.61, 70.92, 71.50, 71.91, 120.72, 123.32, 132.91, 133.35, 137.37, 142.77.

MS (EI, 80 eV, 120 °C): m/z (%) = 823.4 (6.82) [M + Na]+, 801.4 (4.12) [M]+.

EA C36H64Br2O9 Calcd: C 54.00, H 8.06;

(801.00) Found: C 53.66, H 7.72.


124

Poly(5-dodecyl-2-[2-(2-methoxy-ethoxy)-1-(2-methoxy-ethoxymethyl)-ethoxymethyl]-4,4’-

biphenylene) (52)

C1 2H25

O

OO

OO

OO

OO

n


dioxaborinan-2-yl)benzene 45 (0.156 g, 0.63 mmol), TBAB (0.180 g, 0.626 mmol), NaHCO3

(1.0 g), Pd[P(p-tolyl)3]3 (3.8 mg, 0.6 mol%), THF (25 mL) and water (10 mL).

Yield: 0.408 g (91%). 1H NMR (CDCl3, 500 MHz): δ = 0.84 (broad, 3H, –CH3), 1.22 (broad, 18H, –CH2–), 1.52

(broad, 2H, β-CH2), 1.85 (broad, 2H, –CH2–), 2.66 (broad, 2H, α-CH2), 3.33 (broad, 6H, OCH3),

3.59 (broad, 28H, –OCH2CH2–), 3.74 (broad, 1H, -OCH-), 4.65 (broad, 2H,–CH2Br), 7.30

(broad, 1H, aromatic-H), 7.42 (broad, 1H, aromatic-H), 7.48 (broad, 4H, aromatic-H). 13C NMR (CDCl3, 63.5 MHz): δ = 14.81, 20.61, 23.38, 25.11, 30.06, 30.38, 32.62, 33.67, 59.69,

79.32, 129.85, 131.83, 132.58, 133.60, 140.84, 141.40.

EA (C42H70O9)n Calcd: C 70.16, H 9.81;

(718.50)n Found: C 69.21, H 9.47.

(R)- 2,5-Dibromo-4-(2-methylbutoxy)phenol (54)

BrBr

O

HO

*

Synthesis method A (see 5.2.1): 2,5-Dibromohydroquinone 23 (8.8 g, 33.1 mmol), NaOH (2.0 g,

50 mmol), dry ethanol (200 mL), (S)-(+)-1-Bromo-2-methylbutane 53 (5.0 g, 33.1 mmol) and


125

conc. HCl (3.4 mL). The crude product was purified by column chromatography through silica

gel (hexane/ethyl acetate, 97:03).

Yield: 7.02 g (63%).

M. p. 70-71 °C.

Rf = 0.48 (hexane/ethyl acetate, 97:03). 1H NMR (CDCl3, 300 MHz): δ = 0.96 (t, 3H, J = 7.2, δ-OPh), 1.06 (d, 3H, J = 6.9, γ-OPh), 1.33

(m, 2H, -CH2CH3-), 1.94 (m, 1H, chiral- H), 3.83 (m, 2H, –OCH2), 5.13 (b, 1H, –OH), 6.99 (s,

1H, aromatic- H), 7.27 (s, 1H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ =11.26, 16.51, 26.05, 34.80, 75.06, 108.34, 112.53, 116.53,

120.30, 146.74, 150.26.

MS (EI, 80 eV, 200 °C): m/z (%) = 337.93 (10.56) [M]+, 267.85 (100.00) [M – C5H12]+, 71.08

(7.05) [M – C6H6Br2O2]+, 43.06 (31.09) [CH2CH2CH3]+.

EA C11H14Br2O2 Calcd: C 39.08, H 3.95;

(338.04) Found: C 39.10, H 4.17.

(R)-1-(1,3-Bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)propan-2-yloxy)-2,5-dibromo-4-(2-

methylbutoxy)benzene (55)

O

O

O

Br Br

O

OO

OO

OO

*

Synthesis method D (see 5.2.1): Compound 54 (0.73 g, 2.16 mmol), activated mesylate 29 (1.0 g,

2.16 mmol), K2CO3 (0.58 g, 4.20 mmol) and acetonitrile (80 mL). The crude product was

purified by silica gel column chromatography (CH2Cl2/CH3OH, 97:3) gave a colorless oil.

Yield: 1.24 g (81.3%).


126

Rf = 0.37 (CH2Cl2/CH3OH, 97:3). 1H NMR (CDCl3, 500 MHz): δ = 0.96 (t, 3H, J = 7.2, δ-OPh), 1.06 (d, 3H, J = 6.9, γ-OPh), 1.33

(m, 2H, -CH2-), 1.94 (m, 1H, -OCH2CH(CH3)C2H5), 3.40 (s, 6H, -OCH3), 3.56 (m, 2H, –OCH2),

3.66-3.82 (m, 28H, -OCH2CH2O-), 4.38 (quin, 1H, -OCH), 7.03 (s, 1H, aromatic- H), 7.43 (s,

1H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 11.25, 16.44, 25.98, 29.63, 34.69, 53.56, 58.88, 70.40, 70.48,

70.56, 70.69, 71.08, 71.85, 74.62, 76.81, 80.86, 110.93, 112.70, 117.70, 122.78, 149.58, 150.98.

MS (EI, 80 eV, 180 °C): m/z (%) = 704.1 (3.10) [M]+, 147.1 (48.21) [C7H15O3]+, 103.2 (41.03)

[C5H11O2]+, 59.20 (100) [C3H7O]+.

EA C28H48Br2O10 Calcd: C 47.74, H 6.87;

(704.48) Found: C 47.94, H 6.82.

Poly[(R)-5-(2-methylbutoxy)-2-(2-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-1-{2-[2-(2-

methoxy-ethoxy)-ethoxy]-ethoxymethyl}-ethoxy)-4,4’-biphenylene] (56)

O

O

OO

OO

OO

OO

n

*


dioxaborinan-2-yl)benzene 45 (0.173 g, 0.70 mmol), NaHCO3 (1.0 g), THF (25 mL), water (10

mL) and Pd[P(p-tolyl)3]3 (4.22 mg, 0.6 mol%).

Yield: 0.409 g (93%). 1H NMR (CDCl3, 500 MHz): δ = 0.94 (broad, 3H, –CH3), 1.02 (broad, 3H, -CH3), 1.27 (broad,

2H, -CH2-), 1.87 (broad, 1H, -OCH2CH(CH3)C2H5), 3.31 (broad, 6H, -OCH3), 3.46 (broad, 2H, –


127

OCH2), 3.56-3.69 (broad, 28H, -OCH2CH2O-), 4.52 (broad, 1H, OHCH), 7.09 (broad, 1H,

aromatic- H), 7.27 (broad, 1H, aromatic-H), 7.72 (broad, 4H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 13.60, 13.98, 19.74, 22.56, 24.28, 26.05, 29.23, 29.54, 31.80,

58.87, 59.28, 69.80, 70.51, 71.89, 76.47, 76.98, 77.48, 116.24, 117.01, 129.01, 130.56, 136.87,

150.15, 150.85.

EA (C34H52O10)n Calcd: C 65.57, H 8.74;

(620)n Found: C 65.35, H 8.48.

6-(2, 5-Dibromo-4-hexyloxy-phenoxy)-hexan-1-ol (58)

BrBr

OC6H13

O

OH In a three neck flask, 2,5-dibromo-4-(hexyloxy)phenol 57 (10 g, 28.5 mmol), K2CO3 (5.81 g, 42.7

mmol) in 300 mL acetonitrile were degassed and heated to 80 °C. When the solution turn

homogenous, 1-bromo-hexan-6-ol (5.17 g, 28.5 mmol) was added and reaction mixture was

refluxed for 12 h. The solvent was removed and the residue was dissolved in H2O. It was

extracted with CH2Cl2 and the organic layer was dried over anhydrous MgSO4, filtered and

solvent was evaporated on rotary evaporator. The chromatographic separation on silica gel in

hexane/ethyl acetate (3:1) gave the desired product.

Yield: (8.64 g, 67%).

M. p. 68 °C.

Rf = 0.46 (hexane/ethyl acetate, 3:1). 1H NMR (CDCl3, 250 MHz): δ = 0.92 (t, J = 7.0 Hz, 3H), 1.47 (m, 8H), 1.79 (m, 6H), 2.03 (m,

2H), 3.59 (t, 2H, J = 6.5 Hz, α-OH) 3.91 (t, 4H, -OCH2), 5.02 (br, 1H, -OH) 7.06 (s, 2H,

aromatic-H). 13C NMR (CDCl3, 62.896 MHz): δ = 14.54, 23.03, 26.06, 29.69, 31.51, 33.33, 63.03, 70.30,

76.96, 110.90, 118.78, 150.09.

MS (EI, 80 eV, 200 °C): m/z (%) = 450.2 (8.89) [M]+, 351.5 (10.67) 477.9 (7.09) [M – C6H12O]+,

267.7 (100.00) [M – C12H24O]+.


128

EA C18H28Br2O3 Calcd: C 47.81, H 6.29; (452) Found: C 48.13, H 5.99.

1,4-Dibromo-2-hexyloxy-5-(6-iodo-hexyloxy)-benzene (59)

BrBr

OC6H13

O

I Iodine crystals (0.48 g, 3.3 mmol) were added portionwise to a solution of triphenyl phosphine

(0.87 g, 3.3 mmol) in CH2Cl2 (100 mL) at 0 °C and stirred for 5 min. To this resulting yellow

slurry was added dropwise over 10 min a solution of compound 58 (1.0 g, 2.2 mmol) and

imidazole (0.453 g, 6.7 mmol) in CH2Cl2 (50 mL). After being stirred for 2 h at room

temperature, the reaction mixture was diluted with CH2Cl2 and washed successively with 5%

NaHSO3 (200 mL), H2O (200 mL) and brine (200 mL), dried with MgSO4, and filtered through

pad of silica gel and washing with additional 300 mL of CH2Cl2. The filtrate was concentrated to

get a white solid and purified by column chromatography using solvent mixture hexane/ethyl

acetate (5:1) to afford the pure product.

Yield: 1.04 g (84%).

M.p. 62-63 °C.

Rf = 0.51 (hexane/ethyl acetate, 5:1). 1H NMR (CDCl3, 250 MHz): δ = 0.91 (t, J = 7.0 Hz, 3H), 1.36 (m, 8H), 1.48 (m, 6H), 1.84 (m,

2H), 3.66 (t, 2H, J = 6.5 Hz - α-I) 3.97 (m, 4H, -OCH2), 7.11 (s, 1H, aromatic-H), 7.33 (s, 1H,

aromatic-H).

13C NMR (CDCl3, 62.896 MHz): δ = 7.27, 14.54, 22.42, 26.06, 29.69, 31.51, 33.93, 70.90,

111.17, 118.52, 150.14.

MS (EI, 80 eV, 40 °C): m/z (%) = 561.9 (41.37) [M]+, 477.9 (7.09) [M – C6H12]+, 267.7 (100.00)

[M – C12H24I]+.

EA C18H27Br2IO2 Calcd: C 38.46, H 4.84;

(562.12) Found: C 38.84, H 4.70.


129

6-(2,5-Dibromo-4-hexyloxy-phenoxy)-hexyl]-phosphonic acid diethyl ester (60)

BrBr

OC6H13

O

P OEtOOEt

A slurry of compound 59 (4.0 g, 7.1 mmol) in triethyl phosphite (40.0 g, 24 mmol) was heated

until all solid was dissolved and a gentle reflux began (~ 60-70 °C) evolving ethyl iodide. The

reflux was continued for 16 h. After cooling, the excess of triethylphosphine was removed by

distillation under vacuum. The product was dried completely under high vacuum pump.

Yield: 3.8 g (93%)

M.p. 54-56 °C. 1H NMR (CDCl3, 250 MHz): δ = 0.71 (t, J = 7.0 Hz, 3H), 0.97 (t, 6H, -OCH2CH3), 1.03 (m, 8H),

1.58 (m, 4H), 1.79 (m, 6H), 1.32 (m, 2H), 3.76 (t, 2H, -OCH2,) 3.92 (t, 4H, -OCH2 ), 6.95 (s, 2H,


76.96, 110.90, 118.18, 150.30.

MS (EI, 80 eV, 200 °C): m/z (%) = 595.1 (2.43) [M + Na]+, 573.2 (16.20) [M]+, 561.94 (3.56)

[C18H27Br2IO2]+.

E. A C22H37Br2O5P Calcd: C 46.17, H 6.52;

(572.31) Found: C 46.72, H 6.58.

Phosphonic acid ester functionalized amphiphilic polymer (61) OC6H13

O

P OEtOOEt

n


130

Synthesis method E (see 5.2.1): Monomer 60 (0.49 g, 0.86 mmol), 1,4-di(1,3,2-dioxaborinan-2-

yl)benzene 45 (0.21 g, 0.86 mmol), NaHCO3 (1.0 g), THF (25 mL), water (10 mL) and Pd[P(p-

tolyl)3]3 (5.2 mg, 0.6 mol%).

Yield: 0.381 g (89%). 1H NMR (CDCl3, 250 MHz): δ = 0.71 (broad, 3H), 0.97 (broad, 6H, -OCH2CH3), 1.03 (broad,

8H, -CH2-), 1.79 (broad, 6H,), 1.32 (broad, 2H), 1.58 (broad, 2H), 3.76 (broad, 2H, -OCH2,) 3.92

(broad , 4H, -OCH2CH3 ), 6.95 (broad, 2H, aromatic -H), 7.34 ( broad, 4H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 16.45, 16.53, 22.40, 22.46, 22.63, 24.73, 25.70, 25.82, 26.59,

29.18, 29.36, 30.21, 30.43, 31.51, 61.36, 61.45, 69.45, 69.60, 116.25, 129.09, 130.51, 137.01,

150.33, 150.51.

E. A. (C28H41O5P)n Calcd: C 68.55, H 8.72;

(491)n Found: C 67.11, H 8.69.

Phosphonic acid functionalized amphiphilic polymer (62) OC6H13

O

P OHOOH

n

Polymer 61 (0.2 g, 0.4 mmol) was dissolved in CH2Cl2. Bromotrimethylsilane (0.22 mL, 1.6

mmol) and triethylamine (0.24 mL, 1.6 mmol) were added and the solution was stirred for 12 h.

The solvent was removed under vacuum and methanol (15 mL) was added. The resulting purple

suspension was stirred for 8 h. The traces of solvent & reagent were removed in vacuo. The

phosphonic acid containing polymer was insoluble in organic solvents as well as in water but it

could be solubilized as its tetraalkylammonium salt solution in water.


131

Tert-butyl 3,3’-(5-((2,5-dibromo-4-(hexyloxy)phenoxy)methyl)-1,3-phenylene)bis(oxy)

bis(propane-3,1-diyl)dicaramate (65)

O

O

O

NHBoc

BocHN

Br Br

OC6H13

2,5-Dibromo-4-(hexyloxy)phenol 57 (1.0 g, 2.84 mmol), triphenylphosphine (0.74 g, 2.84

mmol), and (3,5-bis(3-(pivaloyloxyamino)propoxy)phenyl)methanol 64 (1.29 g, 2.84 mmol)

were dissolved in dry THF (40 mL). DEAD (1.236 mL, 2.84 mmol) in 10 mL of dry THF was

added dropwise under exclusion of light. The mixture was stirred for 1 d at room temperature,

diluted with water, and extracted with CH2Cl2. The organic layer was washed with water and

brine, dried over Na2SO4, and concentrated in vacuo. The residue was purified by flash column

chromatography (CH2Cl2/CH3OH, 98: 02) to give a colorless solid.

Yield: 1.51 g (67%).

Rf = 0.56 (CH2Cl2/CH3OH, 98: 02).

M. p. 101-103 °C. 1H NMR (CDCl3, 300 MHz): δ = 1.24 (t, 3H, J = 6.9 Hz, –CH3), 1.36 (m, 6H, -CH2CH2-), 1.45

(s, 18H, C(CH3)3), 1.81(m, 2H, OCH2CH2-), 1.98 (m, 4H, CH2), 3.32 (t, 4H, CH2NHBoc), 3.96

(t, 2H,–OCH2), 3.99 (t, 4H, PhOCH2), 4.81 (br, 2H, NH), 4.99 (s, 2H, OCH2Ph), 6.40 (t, 1H,

aromatic-H), 6.61 (d, 2H, aromatic), 7.11-14 (d, 2H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 14.02, 22.56, 25.60, 28.42, 29.05, 29.52, 31.46, 38.04, 65.78,

70.23, 71.81, 79.25, 101.06, 105.55, 111.10, 118.30, 119.32, 138.66, 149.41, 150.61, 156.03,

160.15.

MALDI-FT-MS (3-HPA): m/z (%) = 827 (1.27) [M + K]+, 811 (100) [M + Na]+, 789 (8.05)

[M]+. EA C35H52Br2N2O8 Calcd: C 53.31, H 6.65, N 3.55;

(788.60) Found: C 53.41, H 6.58, N 3.57.


132

AA-BB type Boc-protected polymer (66)

O

O

O

NHBoc

BocHN

OC6H13

n

Synthesis method E (see 5.2.1): Macromonomer 65 (0.512 g, 0.65 mol), 1,4-di(1,3,2-dioxa-

borinan-2-yl)benzene 45 (0.159 g, 0.65 mol), NaHCO3 (1.0 g), THF (25 mL), water (10 mL) and

Pd[P(p-tolyl)3]3 (3.87 mg, 0.6 mol%).

Yield: 0.437 g (98%). 1H NMR (CDCl3, 500 MHz): δ = 0.88 (broad, 3H, –CH3), 1.27 (broad, 6H, -CH2CH2-), 1.41

(broad, 18H, C(CH3)3), 1.76 (broad, 2H, OCH2CH2-), 1.86 (broad, 4H, CH2), 3.23 (broad, 4H,

CH2NHBoc), 3.89 (broad, 2H,–OCH2), 4.01 (broad, 4H, PhOCH2), 4.80 (broad, 2H, NH), 5.01

(broad, 2H, OCH2Ph), 6.34 (broad, 1H, aromatic-H), 6.49 (broad, 2H, aromatic-H), 7.11-16

(broad, 2H, aromatic-H), 7.69 (broad, 4H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 14.04, 22.59, 25.63, 25.80, 28.43, 29.32, 29.47, 31.49, 37.98,

65.81, 69.64, 71.84, 79.12, 100.93, 105.33, 116.04, 117.40, 129.26, 139.76, 149.94, 151.00,

156.01, 160.04.

EA (C41H56N2O8)n Calcd: C 69.66, H 8.27, N 3.96;

(705.00)n Found: C 69.72, H 8.04, N 3.86.

AA-BB type deprotected polymer (67)

O

O

O

NH3+ CF3COO-

-OOCF3C +H3N

OC6H13

n


133

To compound 66 (0.20 g, 0.283 mmol), TFA (10 mL) was added. After stirring for 12 h at room

tempearture, CH2Cl2 (1 mL) and TFA (2 mL) were added to the mixture and stirring was

continued for 7 d. Precipitation in methanol gave 67 as blue colored film.

Yield: 0.202 g (97%). 1H NMR (CDCl3, 500 MHz): δ = 0.86 (broad, 3H, –CH3), 1.27 (broad, 6H, -CH2CH2-), 1.74

(broad, 2H, OCH2CH2-), 2.08 (broad, 4H, -CH2), 3.09 (broad, 4H, CH2NH3+), 4.03 (broad, 2H,–

OCH2), 4.03 (broad, 4H, PhOCH2), 4.88 (broad, 2H, NH), 5.10 (broad, 2H, OCH2Ph), 6.44

(broad, 1H, aromatic-H), 6.60 (broad, 2H, aromatic-H), 7.18 (broad, 2H, aromatic-H), 7.74

(broad, 4H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 13.26, 22.31, 25.51, 26.97, 28.84, 29.03, 31.36, 37.20, 63.63,

64.93, 100.01, 105.18, 111.03, 114.91, 122.67, 129.11, 144.04, 159.79, 161.50.

EA (C35H42F6N2O8)n Calcd: C 57.22, H 6.04, N 3.81;

(732.00)n Found: C 55.50, H 6.02, N 3.58.

Tert-butyl 3,3’,3’’,3’’’-(5,5’-(2,5-dibromo-1,4-phenylene)bis(methylene)bis

(benzene-5,3,1-triyl))tetrakis(oxy)tetrakis(propane-3,1-diyl)tetracarbamate (68)

O

O

O

BocHN

NHBoc

BrBr

O

O

O

BocHN

NHBoc 2,5-Dibromobenzene-1,4-diol 23 (1.0 g, 3.73 mmol), triphenylphosphine (0.97 g, 3.73 mmol),

and (3,5-bis(3-(pivaloyloxyamino)propoxy)phenyl) methanol 64 (1.69 g, 3.73 mmol) were

dissolved in dry THF (40 mL). DEAD (1.62 mL, 3.73 mmol) in 10 mL of dry THF was added

dropwise under exclusion of light. The mixture was stirred for 1 d at room temperature, diluted


134

with water, and extracted with CH2Cl2. The organic layer was washed with water and brine, dried

over Na2SO4, and concentrated in vacuo. The residue was purified by flash column

chromatography (CH2Cl2/CH3OH, 97: 03) to give colorless solid.

Yield: 3.11 g (73%).

M. p. 166-167 °C.

Rf = 0.63 (CH2Cl2/CH3OH, 97: 03). 1H NMR (CD2Cl2, 300 MHz): δ = 1.46 (s, 36H, C(CH3)3), 1.81 (m, 8H, OCH2CH2-), 3.32 (t,

8H, CH2NHBoc), 4.05 (t, 8H, PhOCH2), 4.81 (broad, 4H, NH), 5.04 (s, 4H, OCH2Ph), 6.46 (t,

2H, aromatic-H), 6.65 (d, 4H, aromatic-H), 7.24 (d, 2H, aromatic-H). 13C NMR (CD2Cl2, 75.5 MHz): δ = 28.52, 30.01, 38.27, 66.34, 72.18, 79.19, 101.43, 106.10,

111.78, 119.47, 139.01, 150.38, 156.38, 160.69.

MALDI-FT-MS (3-HPA): m/z (%) = 1179 (16.22) [M + K]+, 1163 (58.80) [M + Na]+.

EA C52H76Br2N4O14 Calcd: C 54.74, H 6.71, N 4.91;

(1140.99) Found: C 54.11, H 6.69, N 4.80.

AA-BB type Boc-protected polymer (69)

O

O

O

BocHN

NHBoc

O

O

O

BocHN

NHBoc

n

Synthesis method E (see 5.2.1): Compound 68 (0.495 g, 0.43 mol), 1,4-di(1,3,2-dioxaborinan-2-

yl)benzene 45 (0.106 g, 0.43 mol), NaHCO3 (1.0 g), THF (25 mL), water (10 mL) and Pd[P(p-

tolyl)3]3 (2.60 mg, 0.6 mol%).

Yield: 0.417 g (90%).


135

1H NMR (CDCl3, 500 MHz): δ = 1.42 (broad, 36H, C(CH3)3), 1.85 (broad, 8H, OCH2CH2-), 3.19

(broad, 8H, CH2NHBoc), 3.90 (broad, 8H, PhOCH2), 4.96 (broad, 4H, NH), 5.07 (broad, 4H,

OCH2Ph), 6.36 (broad, 2H, aromatic-H), 6. 52 (broad, 4H, aromatic-H), 7.2 (broad, 2H,

aromatic-H), 7.76 (broad, 4H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 28.42, 29.49, 37.92, 65.79, 71.65, 79.10, 100.93, 105.34,

117.14, 129.35, 131.14, 136.96, 139.62, 150.42, 156.03, 160.05.

EA (C58H80N4O14)n Calcd: C 65.76, H 7.80, N 5.29;

(1057)n Found: C 65.83, H 7.67, N 5.19.

AA-BB type deprotected polymer (70)

O

O

O

+H3N

NH3+

O

O

O

+H3N

NH3+

n

CF3COO-

CF3COO-

CF3COO-

CF3COO- To compound 69 (0.50 g, 0.47 mmol), TFA (10 mL) was added. After stirring for 12 h at room

temperature, CH2Cl2 (1 mL) and TFA (2 mL) were added to the mixture and stirring was

continued for 7 d. Precipitation in methanol gave 70 as blue colored film. Yield: 0.5 g (94%). 1H NMR (CDCl3, 500 MHz): δ = 2.04 (broad, 8H, OCH2CH2-), 3.08 (broad, 8H, CH2NH3

+), 3.97

(broad, 8H, PhOCH2), 4.92 (broad, 4H, NH), 5.14 (broad, 4H, OCH2Ph), 6.43 (broad, 2H,

aromatic-H), 6. 59 (broad, 4H, aromatic-H), 7.31 (broad, 2H, aromatic-H), 7.80 (broad, 4H,


118.56, 137.12, 139.91, 150.30, 159.75.

EA (C46H54F12N4O14)n Calcd: C 49.56, H 4.88, N 5.03;

(1113)n Found: C 47.93, H 4.82, N 4.59.


136

2,5-Dibromo-4-(2-bromoethoxy)phenol (72) O

HO

Br

Br

Br

Synthesis method B (see 5.2.1): 2,5-Dibromohydroquinone 23 (10.0 g, 37.5 mmol), NaOH (1.50

g, 37.5 mmol), dry ethanol (200 mL) and ethylene dibromide 71 (4.69 g, 37.5 mmol). The crude

product was purified by column chromatography (hexane/ethyl acetate, 95: 05).

Yield: 8.76 g (62%) colorless solid.

M. p. 106-107 °C.

Rf = 0.57 (hexane/ethyl acetate, 95: 05). 1H NMR (CDCl3, 300 MHz): δ = 3.67 (t, 2H, J = 6.6 Hz, -CH2Br), 4.28 (t, 2H, J = 6.3 Hz,-

OCH2-), 5.27 (b, 1H, -OH), 7.07 (s, 1H, aromatic-H), 7.27 (s, 1H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 28.57, 70.61, 108.46, 113.28, 118.45, 120.45, 147.87, 149.14.

MS (EI, 70 eV, 200 °C): m/z (%) = 373.79 (65.01) [M]+, 267.85 (100) [M – C3H5Br ]+, 186.93

(3.53) [M – C3H5Br2 ]+.

EA C8H7Br3O2 Calcd: C 25.63, H 1.88;

(374.85) Found: C 25.82, H 1.94.

Tert-butyl 3,3’,3’’,3’’’-(5,5’-(3,3’-(5-(bromomethyl)-1,3-phenylene)bis(oxy)bis(propane-

3,1-diyl))bis(azanediyl)bis(oxomethylene)bis(benzene-5,3,1-triyl))tetrakis(oxy)tetrakis

(propane-3,1-diyl)tetracarbamate (75)

Br

O O

NHHN

O OO

O O

O

NHBoc

NHBoc NHBoc

NHBoc

To a mixture of the dendritic benzyl alcohol 74 (1.0 g, 0.865 mmol) and carbon tetrabromide

(0.373 g, 1.12 mmol) in the minimum amount of dry tetrahydrofuran was added to

triphenylphosphine (0.294 g, 1.12 mmol) in dry tetrahydrofuran. The reaction mixture was stirred


137

under nitrogen for 2 h at room temperature. After all the starting material was consumed (TLC),

the reaction mixture was then poured into water and extracted with CH2CI2 (3 × 50 mL). The

combined extracts were dried and evaporated to dryness. The crude product was then purified by

using silica gel column chromatography (ethyl acetate, 100%).

Yield: 0.83 g (78%).

Rf = 0.81 (ethyl acetate). 1H NMR (CDCl3, 300 MHz): δ = 1.45 (s, 36H, C(CH3)3), 1.97 (m, 8H, CH2CH2NHBoc), 2.12

(m, 4H, CH2CH2NHBoc), 3.30 (t, 8H, CH2NHBoc), 3.66 (t, 4H, CH2NHBoc), 4.01 (t, 8H,

PhOCH2), 4.15 (t, 4H,PhOCH2), 4.40 (s, 2H, PhCH2Br), 4.85 (br, 4H, NH), 6.40 (t, 1H, aromatic-

H), 6.55 (d, 4H, aromatic-H), 6.85 (t, 2H, NH), 6.91 (d, 4H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 21.00, 28.39, 28.90, 29.48, 33.46, 37.71, 60.36, 65.81, 66.37,

79.17, 101.60, 104.37, 105.70, 107.68, 136.72, 139.82, 156.10, 159.93, 167.40.

MALDI-FT-MS (3-HPA): m/z (%) = 1257.52 (6.19) [M + K]+, 1241.54 (38.56) [M + Na]+.

Tert-butyl 3,3’,3’’,3’’’-(5’,5’-(3,3’-(5-((2,5-dibromo-4-(2-bromoethoxy)phenoxy)methyl)

-1,3-phenylene)bis(oxy)bis(propane-3,1-diyl))bis(azane diyl)bis(oxomethylene)bis

(benzene-5,3,1-triyl))tetrakis(oxy)tetrakis(propane-3,1-diyl)tetracarbamate (76)

O

O O

NHHN

O OO

O O

O

NHBoc

NHBoc NHBoc

NHBoc

Br

BrOCH2CH2Br

Compound 72 (1.0 g, 3.73 mmol), triphenylphosphine (0.97 g, 3.73 mmol), and tert-butyl

3,3',3'',3'''-(5,5'-(3,3'-(5-(hydroxymethyl)-1,3-phenylene)bis(oxy)bis(propane3,1-diyl))bis

(azanediyl)bis(oxomethylene)bis(benzene-5,3,1-triyl))tetrakis(oxy)tetrakis(propane-3,1-diyl)


138

tetracarbamate 74 (1.69 g, 3.73 mmol) were dissolved in dry THF (40 mL). DEAD (1.62 mL,

3.73 mmol) in 10 mL of dry THF was added dropwise under exclusion of light. The mixture was

stirred for 1 d at room temperature, the solvent evaporated, and the crude product purified by

flash column chromatography (CH2Cl2/CH3OH, 97: 03).

Yield: 3.11 g (73%) of a colorless solid.

M. p. 148-149 °C.

Rf = 0.42 (CH2Cl2/CH3OH, 97: 03). 1H NMR (CD2Cl2, 300 MHz): δ = 1.46 (s, 36H, C(CH3)3), 1.97 (m, 8H, CH2CH2, NHBoc), 2.15 (m, 4H, CH2CH2NHBoc), 3.32 (t, 8H, CH2NHBoc), 3.67 (t, 4H, CH2NHBoc), 3.67 (t, 2H, J

= 6.6 Hz, β-OPh), 4.04 (t, 8H, PhOCH2), 4.09 (t, 4H, PhOCH2), 4.30 (t, 2H, J = 6.3 Hz, α-OPh),

4.82 (br, 4H, NH), 5.02 (s, 2H, OCH2Ph), 6.46 (t, 2H, aromatic-H), 6.65 (d, 4H, aromatic-H),

6.84 (t, 1H, aromatic-H), 7.09 (d, 2H, aromatic-H), 7.24 (d, 2H, aromatic-H). 13C NMR (CD2Cl2, 75.5 MHz): δ = 28.42, 28.54, 28.88, 29.52, 37.98, 65.92, 66.62, 70.38, 71.60,

79.35, 101.53, 104.48, 105.67, 111.54, 111.89, 119.07, 119.86, 136.84, 138.65, 149.63, 150.35,

156.05, 160.01, 167.32.

MALDI-FT-MS (3-HPA): m/z (%) = 1535.96 [M + Na]+, 1513.70 [M + H]+.


(1512.21) Found: C 53.37, H 6.39, N 5.54.


139

Tert-butyl 3,3’,3’’,3’’’-(5,5'-(3,3'-(5-((2,5-dibromo-4-(vinyloxy)phenoxy)methyl)-1,3-

phenylene)bis(oxy)bis(propane-3,1-diyl))bis(azanediyl)bis(oxomethylene)bis(benzene-

5,3,1-triyl))tetrakis(oxy)tetrakis(propane3,1-diyl)tetracarbamate (77)

O

O O

NHHN

O OO

O O

O

NHBoc

NHBoc NHBoc

NHBoc

Br

BrO

Synthesis method C (see 5.2.1): KOtBu (0.11 g, 0.99 mmol), 1,3-bis(3,6,9-trioxadecanyl)

glycerol 28 (0.38 g, 0.99 mmol), THF (50 mL) and compound 76 (1.5 g, 0.99 mmol). The crude

product purified by flash column chromatography (CH2Cl2/CH3OH, 99: 01).

Yield: 1.07 g (75%) of a colorless solid.

M. p. 76-77 °C.

Rf = 0.76 (CH2Cl2/CH3OH, 99: 01). 1H NMR (CDCl3, 300 MHz): δ = 1.45 (s, 36H, C(CH3)3), 1.97 (m, 8H, CH2CH2NHBoc), 2.15

(m, 4H, CH2CH2NHBoc), 3.32 (t, 8H, CH2NHBoc), 3.67 (t, 4H, CH2NHBoc), 4.01 (t, 8H,

PhOCH2), 4.13 (t, 4H, PhOCH2), 4.48 (dd, 1H, J = 2.1 Hz, cis-H), 4.66-4.70 (dd, 1H, J = 2.1 Hz,

trans-H), 4.84 (broad, 2H, NH), 5.04 (s, 2H, OCH2Ph), 6.44 (t, 1H, aromatic-H), 6.50 (d, 2H,

aromatic-H), 6.53 (t, 1H, CH=CH2), 6.65 (t, 2H, aromatic-H), 6.80 (t, 2H, aromatic-H), 6.91 (d,

4H, aromatic-H), 7.15 (s, 1H, aromatic-H), 7.28 (s, 1H, aromatic-H). 13C NMR (CD2Cl2, 75.5 MHz): δ = 28.42, 28.94, 29.50, 37.76, 65.83, 66.37, 71.42, 79.20, 95.31,

101.40, 104.36, 105.53, 105.72, 111.46, 112.67,118.36, 123.62, 136.76, 138.35, 147.50, 148.58,

151.67, 156.08, 159.93, 160.07, 167.38.

MALDI-FT-MS (3-HPA): m/z (%) = 1470 [M + K]+, 1454 [M + Na]+.


140


(1140.99) Found: C 56.04, H 6.75, N 5.68.

2,5-Dibromo-4-(3-bromopropoxy)phenol (80) OBr

BrHO

Br

Synthesis method B (see 5.2.1): 2,5-dibromohydroquinone 23 (10.0 g, 37.5 mmol), NaOH (1.50

g, 37.5 mmol), dry ethanol (200 mL) and 1,3-dibromopropane 79 (7.53 g, 37.5 mmol). The crude

product was purified by column chromatography (hexane/ethyl acetate, 95: 05).

Yield: 9.16 g (63.12%) of a colorless solid.

M. p. 76-78 °C.

Rf = 0.52 (hexane/ethyl acetate, 95: 05). 1H NMR (CDCl3, 300 MHz): δ = 2.38 (q, 2H, J = 6.0 Hz, -CH2Br), 3.68 (t, 2H, J = 6.3 Hz, -

CH2CH2Br), 4.11 (t, 2H, J = 5.7 Hz, -OCH2-), 5.21 (broad, 1H, -OH group), 7.05 (s, 1H,

aromatic-H), 7.26 (s, 1H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 29.98, 32.24, 67.64, 108.47, 112.61, 116.99, 120.34, 147.22,

149.58.

MS (EI, 70 eV, 200 °C): m/z (%) = 389.81 (21.02) [M]+, 267.85 (100) [M – C3H5Br ]+, 186.93

(3.53) [M – C3H5Br2 ]+.

EA C9H9Br3O2 Calcd: C 27.80, H 2.33;

(388.88) Found: C 27.98, H 2.34.

4-(2,5,8,11-Tetraoxatetradecan-14-yloxy)-2,5-dibromophenol (81) O

Br

BrOH

OO

OO

Tri (ethylene glycol) monomethyl ether 25 (25 mL, 148 mmol) was stirred under nitrogen at 80

°C while sodium (0.118 g, 5.14 mmol) in small portions was added. After all sodium had reacted,

the flask content was cooled to 60 °C. KI (0.05 g, 0.3 mmol) and 2,5-dibromo-4-(3-

bromopropoxy)phenol 80 (1.0 g, 2.57 mmol) in triethylene glycol monomethyl ether 25 (10 mL)

were added dropwise. Stirring was continued at 80 °C for 12 h. After cooling to room


141

temperature, distilled water was added and the mixture was extracted with CH2Cl2. The crude

product was purified by preparative HPLC using chloroform as a eluent.

Yield: 0.76 g (62.5%). 1H NMR (CDCl3, 300 MHz): δ = 2.05 (m, 2H, J = 6.0 Hz, -CH2CH2CH2-), 3.37 (s, 3H, -OCH3),

3.55 (m, 2H, J = 6.3 Hz, -CH2CH2CH2-), 3.69 (m, 12H, -CH2CH2O-), 4.05 (t, 2H, J = 5.7 Hz, -

OCH2CH2CH2-), 6.63 (s, 1H, -OH), 7.01 (s, 1H, aromatic-H), 7.20 (s, 1H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 29.40, 58.92, 66.93, 67.47, 70.17, 70.35, 70.46, 70.49, 71.89,

108.54, 111.52, 117.54, 120.41, 147.83, 149.33.

MALDI-FT-MS (3-HPA): m/z (%) = 495.0 (15.00) [M + K]+, 480.24 (1.22) [M + Na]+, 472.99

(3.33) [M]+.

EA C16H24Br2O6 Calcd: C 40.70, H 5.12;

(472.15) Found: C 40.86, H 5.31.

Tert-butyl 3,3’,3’’,3’’’-(5,5’-(3,3’-(5-((4-(2,5,8,11-tetraoxatetradecan-14-yloxy)-2,5-

dibromophenoxy)methyl)-1,3-phenylene)bis(oxy)bis(propane-3,1-diyl))bis(azanediyl)bis

(oxomethylene)bis(benzene-5,3,1-triyl))tetrakis(oxy)tetrakis(propane-3,1-diyl)tetra

carbamate (82)

Br

Br

O

O

O O

NHHN

OO

O

OBocHN

NHBoc

O

NHBoc

O NHBoc

O

O3


142

Compound 81 (0.387 g, 0.82 mmol), dendritic benzyl bromide 75 (1.0 g, 0.82 mmol) and K2CO3

(0.28 g, 2.05 mmol) were dissolved in 40 ml of dry acetonitrile and the reaction mixture was

refluxed for 24 h under nitrogen atmosphere. After cooling to room temperature, the solvent was

removed on rotary evaporator and the residue mixed with water (50 ml) and then extracted with

CH2Cl2 (3 × 100 mL). The organic layer was dried over anhydrous MgSO4, filtered and the

solvent evaporated. The crude product was purified by column chromatography (ethyl acetate,

100 %).

Yield: 0.96 g (73%).

Rf = 0.73 (ethyl acetate). 1H NMR (CDCl3, 300 MHz): δ = 1.43 (s, 36H, C(CH3)3), 1.94 (m, 8H, CH2CH2, NHBoc), 2.08 (m, 4H, CH2CH2NHBoc), 2.11 (m, 2H, J = 6.0 Hz, -OCH2CH2CH2-), 3.28 (t, 8H,

CH2NHBoc), 3.37 (s, 3H, -OCH3), 3.55 (m, 2H, J = 6.3 Hz, -OCH2CH2CH2-), 3.64 (t, 4H,

CH2NHBoc), 3.70 (m, 12H, -CH2CH2O-), 4.01 (t, 8H, PhOCH2), 4.07 (t, 4H, PhOCH2), 4.11 (t,

2H, J = 5.7 Hz, -OCH2CH2CH2-), 4.91 (broad, 4H, NH), 4.97 (s, 2H, PhCH2O), 6.40 (t, 1H,

aromatic-H), 6.52 (d, 2H, aromatic-H), 6.62 (d, 2H, aromatic-H), 6.91 (d, 4H, aromatic-H), 6.99

(t, 2H, NH), 7.13 (s, 2H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 28.42, 28.89, 29.48, 37.77, 37.90, 59.01, 65.87, 66.51, 66.96,

67.43, 70.31, 70.50, 70.53, 70.58, 71.73, 71.91, 79.23, 101.42, 104.43, 105.67, 111.04, 111.57,

118.34, 110.21, 136.80, 138.78, 136.80, 138.78, 149.45, 150.47, 156.07, 159.97, 160.01, 167.35.

MALDI-FT-MS (3-HPA): m/z (%) = 1647.58 (19.43) [M + K]+, 1631.61 (100) [M + Na]+.


(1610) Found: C 55.07, H 6.95, N 4.81.


143

Amphiphilic AA-BB type Boc-protected polymer (83)

O

O

O

O

NH

HN

O

O

O

O

BocHN

NHBoc

O

NHBoc

O

NHBoc

O

O3

n

Synthesis method E (see 5.2.1): Macromonomer 82 (0.506 g, 0.31 mmol), 1,4-di(1,3,2-


mL) and Pd[P(p-tolyl)3]3 (1.89 mg, 0.6 mol%). Yield: 0.440 g (93 %). 1H NMR (CDCl3, 300 MHz): δ = 1.43 (broad, 36H, C(CH3)3), 1.94 (broad, 8H, CH2CH2NHBoc),

2.08 (broad, 4H, CH2CH2NHBoc), 2.11 (broad, 2H, -OCH2CH2CH2-), 3.28 (broad, 8H,

CH2NHBoc), 3.37 (broad, 3H, -OCH3), 3.55 (broad, 2H, -CH2CH2CH2O-), 3.64 (broad, 4H,

CH2NHBoc), 3.70 (broad, 12H, -CH2CH2O-), 4.01 (broad, 8H, PhOCH2), 4.07 (broad, 4H,

PhOCH2), 4.11 (broad, 2H, -PhOCH2CH2CH2-), 4.91 (broad, 4H, NH), 4.97 (broad, 2H,

PhCH2O), 6.40 (broad, 1H, aromatic-H), 6.52 (broad, 2H, aromatic-H), 6.62 (broad, 2H,

aromatic-H), 6.91 (broad, 4H, aromatic-H), 6.99 (broad, 2H, NH), 7.13 (broad, 2H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 28.42, 28.89, 29.48, 37.77, 37.90, 59.01, 65.87, 66.51, 66.96,

67.43, 70.31, 70.50, 70.53, 70.58, 71.73, 71.91, 79.23, 101.42, 104.43, 105.67, 111.04, 111.57,

118.34, 110.21, 136.80, 138.78, 136.80, 138.78, 149.45, 150.47, 156.07, 159.97, 160.01, 167.35.

EA (C81H116Br2N6O22)n Calcd: C 63.76, H 7.66, N 5.51;

(1525.83)n Found: C 63.98, H 7.83, N 4.44.


144

Amphiphilic AA-BB type deprotected polymer (84)

O

O

O

O

NH

HN

O

O

O

O

-OOCF3C+H3N

NH3+CF3COO-

O

NH3+CF3COO-

O

NH3+CF3COO-

O

O3

n

To polymer 83 (0.2 g, 0.13 mmol), TFA (10 mL) was added. After stirring for 12 h at room

temperature, CH2Cl2 (1 mL) and TFA (2 mL) were added to the mixture and stirring was

continued for 7 d. Precipitation in methanol gave 84 as faint blue colored film.

Yield 0.489 g (%). 1H NMR (CDCl3, 300 MHz): δ = 1.94 (broad, 8H, CH2CH2NH3

+), 2.08 (broad, 4H,

CH2CH2NH3+), 2.11 (broad, 2H, -OCH2CH2CH2-), 3.28 (broad, 8H, CH2 NH3

+), 3.37 (broad, 3H,

-OCH3), 3.55 (broad, 2H, -CH2CH2CH2O-), 3.64 (broad, 4H, CH2NH3+), 3.70 (broad, 12H, -

CH2CH2O-), 4.01 (broad, 8H, PhOCH2), 4.07 (broad, 4H, PhOCH2), 4.11 (broad, 2H, -

PhOCH2CH2CH2-), 4.91 (broad, 4H, NH), 4.97 (broad, 2H, PhCH2O), 6.40 (broad, 1H, aromatic-

H), 6.52 (broad, 2H, aromatic-H), 6.62 (broad, 2H, aromatic-H), 6.91 (broad, 4H, aromatic-H),

6.99 (broad, 2H, NH), 7.13 (broad, 2H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 20.27, 26.89, 27.50, 28.74, 29.34, 37.09, 57.71, 65.12, 67.40,

69.74, 69.94, 71.39, 104.38, 105.84, 129.13, 129.30, 131.62, 131.76, 136.44, 143.19, 143.22,

159.78, 160.16, 160.24, 168.32.

EA (C81H116Br2N6O22)n Calcd: C 52.34, H 5.73, N 5.31;

(1525.83)n Found: C 49.78, H 5.49, N 3.90.


145

(5,5’,5’’,5’’’-(5,5’-(2,5-Dibromo-1,4-phenylene)bis(oxy)bis(methylene)bis(benzene

-5,3,1-triyl))tetrakis(oxy)tetrakis(methylene)tetrakis(benzene-5,3,1-triyl))octakis

(oxy)octakis(methylene)octabenzene (86)

O

O

O O

O O

O

O O

O

O

O

O

O

Br

Br

Synthesis method A (see 5.2.1): 2,5-Dibromohydroquinone 23 (1.0 g, 3.73 mmol), NaOH (0.149

g, 3.73 mmol), dry ethanol (200 mL) and dendritic benzyl bromide 85 (3.011 g, 3.73mmol). The

crude product was purified by column chromatography. Yield: 5.08 g (78%).

Rf = 0.27 (hexane/ethyl acetate; 95:05). 1H NMR (CDCl3, 250 MHz): δ = 4.91 (s, 12H, PhCH2O), 5.16 (s, 16H, PhCH2O, peripheral),

6.30 (t, 4H, aromatic-H), 6.73 (d, 8H, aromatic-H), 7.02 (s, 2H, aromatic-H), 7.38 (m, 24H,

aromatic-H), 7.47 (m, 16H, aromatic-H). 13C NMR (CDCl3, 63 MHz): δ = 70.28, 71.75, 101.77, 102.02, 106.21, 106.50, 111.63, 119.17,

127.68, 127.7, 127.75, 127.80, 128.19, 128.45, 128.60, 128.67, 128.70, 128.72, 128.77, 128.81,

128.83, 136.96, 128.77, 139.42, 150.05, 160.24, 160.36.

MALDI-FT-MS (3-HPA): m/z (%) = 1722.5 (100) [M]+.

EA C104H88Br2O14 Calcd: C 72.55, H 5.15;

(1722) Found: C 72.87, H 4.58.


146

Poly[bis(2,5-bis(3,5-bis(benzyloxy)benzyloxy)benzyloxy)-4,4’-biphenylene] (87)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

n




Yield: 0.466 g (98%). 1H NMR (CDCl3, 500 MHz): δ = 4.92 (broad, 12H, PhCH2O), 5.09 (broad, 16H, PhCH2O,

peripheral), 6.56 (broad, 4H, aromatic-H), 6.63 (broad, 8H, aromatic-H), 6.77 (broad, 2H,

aromatic-H), 7.29-7.47 (broad, 40H, aromatic-H), 7.85 (broad, 4H, aromatic-H). 13C NMR (CDCl3, 63 MHz): δ = 69.78, 69.84, 70.01, 101.47, 101.50, 106.30, 127.44, 127.47,

127.82, 127.93, 128.42, 128.51, 129.08, 129.36, 131.97, 132.06, 136.69, 139.16, 150.81, 159.96.

EA (C110H92O14)n Calcd: C 80.56, H 5.78;

(1638)n Found: C 80.54, H 5.47.


1,3-Dibromo-5-propoxybenzene (98)

BrBr

O


147

3,5-Dibromophenol 97 (5.00 g, 19.84 mmol), NaOH (0.87 g, 21.8 mmol) and n-propyl bromide

(2.68 g, 21.80 mmol) were added in dry ethanol (200 mL). After 6 h of stirring, the reaction

mixture was cooled and filtered. The filtrate was concentrated, distilled water was added and

extracted with CH2Cl2. The crude product was purified by column chromatography through silica

gel (hexane/ethyl acetate, 99:01).

Yield: 5.23 g (89%).

Rf = 0.79 (hexane/ethyl acetate, 99:01). 1H NMR (CDCl3, 250 MHz): δ = 1.05 (t, 3H, J = 7.5 Hz, -CH2CH3), 1.80 (quin, 2H, J = 6.6 Hz, -

CH2CH3), 3.91 (t, 2H, J = 6.6 Hz, -OCH2-), 7.01 (d, 2H, aromatic- H), 7.25 (t, 1H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 10.49, 22.44, 70.09, 116.94, 123.10, 126.16, 160.35.

MS (EI, 70 eV, 200 °C): m/z = 293.90 (26.98) [M]+, 251.85 (100) [M – C4H9]+, 172.94 (7.32) [M

– C4H9Br]+.

EA C9H10OBr2 Calcd: C 36.77, H 3.43;

(294) Found: C 36.87, H 3.44.

1,3-Dibromo-5-butoxybenzene (100)

BrBr

O

3,5-Dibromophenol 97 (2.00 g, 7.93 mmol), NaOH (0.32 g, 7.93 mmol) and butyl bromide (1.19

g, 7.93 mmol) were refluxed in dry ethanol (50 mL). After 6 h of stirring, the reaction mixture

was cooled and filtered. The filtrate was concentrated, distilled water was added and the mixture

extracted with CH2Cl2. The crude product was purified by column chromatography through silica

gel (hexane/ethyl acetate, 99:1) to give 2.14 g of 100 as colorless powder (87%).

Rf = 0.82 (hexane/ethyl acetate, 99:1).

1H NMR (CDCl3, 500 MHz): δ = 1.00 (t, 3H, J =7.5 Hz, -CH2CH3), 1.48 (m, 2H, -CH2CH3),

1.77 (m, 2H, -OCH2CH2-), 3.94 (t, 2H, J = 6.6 Hz, -OCH2CH2-), 7.01 (d, 2H, aromatic-H), 7.25

(t, 1H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 13.81, 19.17, 31.06, 68.33, 116.94, 123.08, 126.16, 160.37.

MS (EI, 70 eV, 200 °C): m/z = 307.92 (23.03) [M]+, 251.86 (100) [M – C4H9]+, 172.94 (1.14) [M

– C4H9Br]+.


148

EA C10H12Br2O Calcd: C 39.00, H 3.93;

(308.01) Found: C 38.91, H 3.96.

Poly[3-butoxy-4’,5-biphenylene] (101)

O

n Synthesis method E (see 5.2.1): 1,3-Dibromo-5-butoxybenzene 100 (4.99 g, 16.22 mol), 1,4-

di(1,3,2-dioxaborinan-2-yl)benzene 45 (3.99 g, 16.22 mol), NaHCO3 (10.0 g), THF (250 mL),

water (100 mL) and Pd[P(p-tolyl)3]3 (99.3 mg, 0.6 mol%). After removal of the solvent, 3.57 g of

polymer 101 formed as a transparent blue emitting film with an intense grewish tone at the glass

wall (98%). For purification it was dissolved in THF (150 mL) and N,N-diethyl-2-

phenylhydrazinecarbothioamide (0.21 g) was added to remove residual Pd traces. The resulting

dark solution was stirred for 1 h at room temperature which did not lead to any significant color

change. The polymer was then precipitated by the addition of methanol (600 mL), filtered and

washed with methanol. After drying in vacuo the obtained material had a lighter, less grewish

appearance than before. For the subsequent fractionation polymer 101 was dissolved in the

minimum amount of CH2Cl2 (125 mL). Methanol (15 mL) was added quickly before the mixture

was allowed to equilibrate for 5 min. Then more methanol (3 mL) was slowly added via a syringe

over a time span of approximately 5 min during which time the first precipitate formed. This was

recovered by filtration through a filter paper. To the remaining solution was again added

methanol (8 mL) which gave the second fraction. Repetition of this process using 6 mL of

methanol afforded the third fraction. All fractions were dried in high vacuum at 20 °C for 10 h.

For quantities and molar masses of the fractions, (see Table 12, Chapter 3.2.3). Fraction 1 was

subjected to four consecutive precipitations in order to improve on its color. After this treatment

the polymer had an almost white appearance. The losses of material were estimated to be 10-15

%. All bulk characterizations were done with this highly purified material.

Yield: 1.352 g (93%).


149

1H NMR (CDCl3, 700 MHz, fraction 1): δ = 1.02 (broad, 3H, -CH2CH3), 1.53 (broad, 2H,

CH2CH3), 1.84 (broad, 2H, OCH2CH2-), 4.12 (broad, 2H, OCH2CH2-), 7.18 (broad, 2H,

aromatic-H), 7.49 (broad, 1H, aromatic-H), 7.75 (broad, 4H, aromatic-H).

13C NMR (CDCl3, 176 MHz, fraction 1): δ = 13.92, 19.34, 31.45, 67.99, 112.42, 118.51, 127.67,

140.37, 142.64, 160.02.

EA (C16H16O)n Calcd: C 85.68, H 7.19;

(224.31)n Found: C 85.40, H 7.09.

Poly[3-hexyloxy-4’,5-biphenylene] (103)

O

n Synthesis method E (see 5.2.1): 1,3-Dibromo-5-(hexyloxy)benzene 102 (2.10 g, 0.62 mmol), 1,4-

di(1,3,2-dioxaborinan-2-yl)benzene 45 (1.53 g, 0.62 mmol), NaHCO3 (1.0 g), THF (100 mL),

water (40 mL) and Pd[P(p-tolyl)3]3 (37 mg, 0.6 mol%). After removal of the solvent, 1.51 g of

polymer 103 formed as a transparent blue emitting film with an intense grewish tone at the glass

wall (96%). For purification it was dissolved in THF (50 mL) and N,N-diethyl-2-





appearance than before. For the subsequent fractionation polymer 103 was dissolved in the

minimum amount of CH2Cl2 (40 mL). Methanol (5 mL) was added quickly before the mixture

was allowed to equilibrate for 5 min. Then more methanol (1 mL) was slowly added via a syringe

over a time span of approximately 5 min during which time the first precipitate formed. This was

recovered by filtration through a filter paper. To the remaining solution was again added

methanol (3 mL) which gave the second fraction. Repetition of this process using 5 mL of

methanol afforded the third fraction. All fractions were dried in high vacuum at 20 °C for 10 h.

Yield: 1.51 g (96%).


150

1H NMR (CDCl3, 500 MHz): δ = 0.91 (broad, 3H, –CH3), 1.37 (broad, 4H, –CH2–), 1.51 (broad,

2H, -OCH2CH2CH2–), 1.85 (broad, 2H, -OCH2CH2CH2–), 4.11 (broad, 2H, -OCH2CH2-), 7.18

(broad, 2H, aromatic-H), 7.50 (broad, 1H, aromatic-H), 7.75 (broad, 4H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 14.11, 22.69, 25.85, 29.40, 31.67, 68.31, 112.43, 118.52,

127.69, 140.40, 142.66, 160.05.

EA (C18H20O)n Calcd: C 85.67, H 7.99;

(252.37)n Found: C 85.13, H 8.21.

Poly[3-hexyloxymethyl-4’,5-biphenylene] (109)

O

n

Synthesis method E (see 5.2.1): 1,3-Dibromo-5-(hexyloxymethyl)benzene 108 (2.05 g, 0.58

mmol), 1,4-di(1,3,2-dioxaborinan-2-yl)benzene 45 (1.44 g, 0.58 mmol), NaHCO3 (1.0 g), THF

(100 mL), water (40 mL) and Pd[P(p-tolyl)3]3 (36 mg, 0.6 mol%). After removal of the solvent,

1.47 g of polymer 109 formed as a transparent blue emitting film with an intense grewish tone at

the glass wall (94%). For purification it was dissolved in THF (50 mL) and N,N-diethyl-2-





appearance than before.

Yield: 1.47 g (94%). 1H NMR (CDCl3, 500 MHz): δ = 0.86 (broad, 3H, –CH3), 1.31 (broad, 4H, –CH2CH2–), 1.41

(broad, 2H, -OCH2CH2CH2–), 1.67 (broad, 2H, -OCH2CH2CH2–), 3.57 (broad, 2H, OCH2CH2-),

4.67 (broad, 2H, –CH2O–), 7.63 (broad, 2H, aromatic-H), 7.78 (broad, 4H, aromatic-H), 7.84

(broad, 1H, aromatic-H).


151

13C NMR (CDCl3, 75.5 MHz): δ = 13.60, 13.98, 19.74, 22.56, 24.28, 26.05, 29.23, 29.54, 31.80,

58.87, 59.28, 69.80, 70.51, 71.89, 76.47, 76.98, 77.48, 116.24, 117.01, 129.01, 130.56, 136.87,

150.15, 150.85.

EA (C19H22O)n Calcd: C 85.67, H 8.32;

(266.39)n Found: C 84.93, H 8.08.

Poly[2,5-(dihexyl)-3’-(hexyloxymethyl)-4,5’-biphenylene] (110)

O

n

Synthesis method E (see 5.2.1): 1,3-Dibromo-5-(hexyloxymethyl)benzene 108 (0.497 g, 1.48

mmol), 2,2'-(2,5-dihexyl-1,4-phenylene)bis(1,3,2-dioxaborinane) 48 (0.614 g, 1.488 mmol),

NaHCO3 (1.0 g), THF (25 mL), water (10 mL) and Pd[P(p-tolyl)3]3 (9.0 mg, 0.6 mol%).

Yield: 0.488 g (93%). 1H NMR (CDCl3, 500 MHz): δ = 0.83 (broad, 6H, -CH2CH3), 0.89 (broad, 3H, -CH2CH3), 1.21

(broad, 14H, -CH2CH2-), 1.30 ( broad, 4H, -CH2CH2-), 1.52 (broad, 4H, -CH2CH2-), 2.67 (broad,

4H, -PhCH2CH2-), 3.53 (broad, 2H, -OCH2CH2-), 4.61 (broad, 2H, PhCH2OCH2-), 7.21 (broad,

2H, aromatic-H), 7.30 (broad, 1H, aromatic-H), 7.34 (broad, 2H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 14.12, 22.57, 29.31, 31.46, 31.59, 32.72, 35.30, 128.12,

129.33, 130.99, 137.55, 139.53, 140.61, 140.70.

EA (C31H48O)n Calcd: C 85.26, H 11.08;

(434.71)n Found: C 85.91, H 10.27.


152

Poly[4,4’-(2’,5’-dihexyl-biphenylene)-co-4,3’-(1’-propyloxy-biphenylene)] (111)

O

n

m

Synthesis method E (see 5.2.1): 1,4-Dibromo-2,5-dihexylbenzene 46 (0.25 g, 0.6184 mmol), 1,4-

di(1,3,2-dioxaborinan-2-yl)benzene 45 (0.304 g, 1.2363 mmol), 1,3-dibromo-5-propoxy-benzene

98 (0.1817 g, 0.6184 mmol), NaHCO3 (1.0 g), THF (25 mL), water (10 mL) and Pd[P(p-tolyl)3]3

(3.7 mg, 0.6 mol%).

Yield: 0.277 g (98%). 1H NMR (CDCl3, 500 MHz): δ = 0.83 (broad, 3H, -CH3), 1.10 (broad, 3H, -CH3), 1.21 (broad,

6H, -CH2CH2-), 1.55 (broad, 2H, -CH2CH2-), 1.90 (broad, OCH2CH2-), 2.65 (broad, 2H, PhCH2-

), 4.09 (broad, 2H, OCH2CH2-), 7.20 (broad, 2H, aromatic-H), 7.49 (broad, 3H aromatic-H), 7.76

(broad, 2H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 10.66, 14.10, 22.56, 22.75, 29.29, 31.58, 32.75, 69.84,

112.41, 118.58, 126.92, 127.69, 128.99, 129.81, 131.02, 137.67, 139.54, 140.37, 141.34, 142.62,

142.92, 160.03.

EA (C33H42O)n Calcd: C 88.25, H 8.73;

(455)n Found: C 85.77, H 8.46.


153

1,3-Dibromo-5-(2-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-1-{2-[2-(2-methoxy-ethoxy)-

ethoxy]-ethoxymethyl}-ethoxymethyl)-benzene (113)

Br Br

O

O O

OO

O O

OO

Synthesis method C (see 5.2.1): KOtBu (0.88 g, 7.8 mmol), 1,3-bis(3,6,9-trioxadecanyl) glycerol

28 (2.0 g, 5.2 mmol), 1,3-dibromo-5-(bromomethyl)benzene 112 (1.7 g, 5.2 mmol) and

anhydrous THF (50 mL). Column chromatography (CH2Cl2/CH3OH, 99:1).

Yield: 2.45 g (76%).

Rf = 0.37 (CH2Cl2/CH3OH, 99:1). 1H NMR (CDCl3, 250 MHz): δ = 3.23 (s, 6H, -OCH3), 3.45 (d, 4H, -CHCH2-), 3.60 (m, 24H, -

OCH2CH2-), 3.64 (m, 1H, OHCH), 4.63 (s, 2H, -PhCH2O-), 7.30 (s, 2H, aromatic-H), 7.53 (s,

1H, aromatic-H). 13C NMR (CDCl3, 63.5 MHz): δ = 8.93, 70.47, 70.56, 70.83, 71.21, 71.62, 71.87, 122.70,

129.03, 132.77, 143.11.

MS (EI, 70 eV, 200 °C): m/z (%)= 632.4 (1.81) [M]+, 103.2 (99.04) [C3H7O]+.

EA C24H40Br2O9 Calcd: C 45.58, H 6.38;

(632.38) Found: C 44.91, H 6.21.


154

Poly[3-(2-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-1-{2-[2-(2-methoxy-ethoxy)-ethoxy]-

ethoxymethyl}-4’,5 -biphenylene] (114)

O

O O

OO

O O

OO

n

Synthesis method E (see 5.2.1): Meta-monomer 113 (0.498 g, 0.79 mmol), 1,4-di(1,3,2-

dioxaborinan-2-yl)benzene 45 (0.193 g, 0.79 mmol), TBAB (0.179 g, 0.79 mmol), NaHCO3 (1.0

g), THF (25 mL), water (10 mL) and Pd[P(p-tolyl)3]3 (4.8 mg, 0.6 mol%).

Yield: 0.394 (91%). 1H NMR (CDCl3, 500 MHz): δ = 3.31 (broad, 6H, -OCH3), 3.63 (broad, 28H, -OCH2CH2-), 3.85

(broad, 1H, -OCH), 4.85 (broad, 2H, PhCH2O-), 7.52 (broad, 1H, aromatic-H), 7.64 (broad, 2H,

aromatic-H), 7.76 (broad, 4H, aromatic-H). 13C NMR (CDCl3, 63.5 MHz): δ = 58.95, 69.35, 70.45, 70.56, 71.85, 72.51, 76.54, 76.62, 77.44,

125.02, 126.83, 127.65, 129.26, 132.16, 140.16, 141.34.

EA (C30H46O9)n Calcd: C 65.43, H 8.42;

(550.31)n Found: C 62.94, H 7.47.

Poly[3-(2,5,8,11-tetraoxadodecane)-4’,5-biphenylene] (116)

O

O

O

n

O


155

Synthesis method E (see 5.2.1): 1-(3,5-Dibromophenyl)-2,5,8,11-tetraoxa-dodecane 115 (0.491 g,

1.19 mmol), 1,4-di(1,3,2-dioxaborinan-2-yl)benzene 45 (0.293 g, 1.19 mmol), NaHCO3 (1.0 g),

THF (25 mL), water (10 mL) and Pd[P(p-tolyl)3]3 (7.0 mg, 0.6 mol%).

Yield: 0.386 g (97%). 1H NMR (CDCl3, 500 MHz): δ = 3.73 (broad, 3H, -OCH3), 3.55 (broad, 2H, -CH2OCH3), 3.67

(broad, 2H, -OCH2CH2O-), 3.71-3.78 (broad, 8H, -OCH2CH2O-), 4.77 (broad, 2H, PhCH2O-),

7.68 (broad, 2H, aromatic-H), 7.82 (broad, 4H, aromatic-H), 7.88 (broad, 1H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 59.04, 69.73, 70.57, 70.67, 70.71, 70.74, 71.95, 73.29,

125.22, 125.58, 127.73, 139.62, 140.19, 140.51.

EA (C20H24O4)n Calcd: C 72.70, H 7.77;

(328)n Found: C 73.20, H 7.82.

1,5-Dibromo-2,4-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)benzene (120)

Br Br

O

O

O

O

O

O

O O

4,6-Dibromobenzene-1,3-diol 119 (5.0 g, 18.8 mol), 2-(2-(2-methoxyethoxy)ethoxy)ethyl

methanesulfonate 117 (9.56 g, 39.40 mol) and K2CO3 (7.78 g, 56.4 mol) were dissolved in the

minimum quantity of DMF and the resulting mixture was refluxed for 24 h. After cooling to

room temperature, the solvent were removed on a rotary evaporator and the residue mixed with

water and then extracted with CH2Cl2 (3 × 100 mL). The organic layer was dried over anhydrous

MgSO4, filtered, and the solvent evaporated. The crude product was purified by column

chromatography using (CH2Cl2/CH3OH, 98:02).

Yield: 8.00 g (76%).

Rf = 0.41 (CH2Cl2/CH3OH, 98:02). 1H NMR (CDCl3, 300 MHz): δ = 3.28 (s, 6H, –OCH3), 3.46 (t, 4H, -OCH2OCH3), 3.56 (t, 8H, -

OCH2CH2O-), 3.69 (t, 4H, -OCH2CH2O-), 3.82 (t, 4H, -OCH2CH2O-), 4.09 (t, 4H, -OCH2CH2O-

), 6.55 (s, 1H, aromatic-H), 7.53 (s, 1H, aromatic-H).


156

13C NMR (CDCl3, 75.5 MHz): δ = 58.92, 69.43, 69.51, 70.44, 70.61, 71.02, 71.11, 71.85, 76.90,

100.81, 103.34, 135.60, 155.44.

MS (EI, 70 eV, 200 °C): m/z (%) = 560.04 (3.10) [M]+, 513.99 (1.06) [M – CH2OCH3]+, 471.99

(1.32) [M – CH2OCH2CH2OCH3]+, 411.95 (1.07) [M – (CH2CH2O)3CH3]+.

EA C20H32Br2O8 Calcd: C 42.88, H 5.76;

(560.27) Found: C 42.85, H 5.79.

Poly[2,4-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-4’,5-biphenylene] (121)

O

O

O

O

O

O

O O

n

Synthesis method E (see 5.2.1): Meta-monomer 120 (0.531 g, 0.95 mmol), 1,4-di(1,3,2-



Yield: 0.401 g (89%). 1H NMR (CDCl3, 500 MHz): δ = 3.34 (broad, 6H, –OCH3), 3.52 (broad, 4H, -OCH2OCH3), 3.64

(broad, 16H, -OCH2CH2O-), 3.85 (broad, 4H, -OCH2CH2O-), 4.21 (broad, 4 H, -OCH2CH2O-),

6.75 (broad, 1H, aromatic-H), 7.48 (broad, 1H, aromatic-H), 7.64 (broad, 4H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 58.94, 68.73, 69.69, 70.39, 70.49, 70.66, 70.88, 71.00, 71.88,

99.88, 123.98, 129.86, 132.11, 142.27, 156.03.

EA (C26H36O8)n Calcd: C 65.25, H 8.00;

(476.26)n Found: C 65.21, H 7.88.

1,3-Dibromo-2-(hexyloxy)benzene (123)

BrBrOC6H13


157

Synthesis method A (see 5.2.1): 2,6-Dibromophenol 122 (5.0 g, 19.84 mol), NaOH (0.95 g, 23.81

mol), 1-bromohexane (3.93 g, 23.81 mol) and dry ethanol (100 mL). The crude product was

purified by column chromatography (hexane/ethyl acetate, 98:02).

Yield: 5.60 g (84%).

Rf = 0.79 (hexane/ethyl acetate, 98:02). 1H NMR (CDCl3, 300 MHz): δ = 0.95 (t, 3H, J = 6.3 Hz, CH3), 1.39 (m, 4H, -CH2CH2CH3-),

1.57 (m, 2H, -OCH2CH2CH2-), 1.91 (m, 2H, J = 6.3 Hz, -OCH2CH2-), 4.03 (t, 2H, J = 6.3 Hz, -

OCH2CH2-), 6.86 (t, 1H, aromatic -H), 7.53 (d, 2H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 14.12, 22.66, 30.04, 31.70, 37.57, 118.61, 126.04, 132.69,

153.60.

MS (EI, 80 eV, 180 °C): m/z = 335.95 (5.56) [M]+, 264.86 (0.71) [M – C5H11]+, 251.85 (100) [M

– C6H13]+, 171.94 (0.96) [M – C5H11Br]+.

EA C12H16Br2O Calcd: C 42.89 H 4.80;

(336) Found: C 43.05 H 4.83.


1,3-Bis(4-bromophenyl)propane (126)

Br Br To a solution of 1,3-bis(4-bromophenyl)propan-2-one 125 (1.0 g, 2.71 mmol) in dry CH2Cl2 (15

mL) and tris(pentafluorophenyl)borane (0.069 g, 0.135 mmol%) was slowly added

polymethylhydrosiloxane (18.47 g, 8.15 mmol) at room temperature. After 10 min, a vigorous

effervescence were observed. The solvent was evaporated and reaction mixture was dissolved in

hexane and filtered through a silica gel column chromatography using hexane as eluent.

Evaporation of the volatiles afforded the reduction product in pure form.

Yield: 0.856 g (89%).

M. p. 61-62 °C. 1H NMR (CDCl3, 300 MHz): δ = 1.93 (m, 2H, -CH2CH2CH2-), 2.61 (t, 4H, J = 7.5 Hz, -

CH2CH2CH2-), 7.08 (d, 4H, J = 8.1 Hz, aromatic-H), 7.44 (d, 4H, J = 8.1 Hz, aromatic-H). 13C NMR (CDCl3, 62.896 MHz): δ = 32.63, 34.70, 119.63, 130.25, 121.46, 140.96.

MS (EI, 70 eV, 200 °C) = 353.94 (43.11) [M]+, 273.01 (1.30) [M - Br]+, 197.98 (6.93) [M –

Br2]+.


158

E. A C15H14Br2 Calcd: C 50.88, H 3.99;

(354) Found: C 50.84, H 4.03.

Polymer (127)

n According to general procedure (method E), 1,3-bis(4-bromophenyl)propane 126 (0.501 g, 1.41

mmol), 1,4-di(1,3,2-dioxaborinan-2-yl)benzene 45 (0.347 g, 1.41 mmol), NaHCO3 (1.0 g), THF

(25 mL), water (10 mL) and Pd[P(p-tolyl)3]3 (8.6 mg, 0.6 mol%) gave an insoluble white powder.

Yield: 0.359 g (99%).

Polymer (128)

n

Synthesis method E (see 5.2.1): 1,3-Bis(4-bromophenyl)propane 126 (0.498 g, 1.41 mmol), 2,2'-

(2,5-dihexyl-1,4-phenylene)bis(1,3,2-dioxaborinane) 48 (0.583 g, 1.41 mmol), NaHCO3 (1.0 g),


Yield: 0.58 g (94 %). 1H NMR (CDCl3, 500 MHz): δ = 0.83 (broad, 6H, –CH3), 1.24 (broad, 14H, –CH2–), 1.49

(broad, 4H, γ-CH2–), 2.11 (broad, 2H, -CH2CH2CH2–), 2.60 (broad, 4H, PhCH2), 2.82 (broad,

4H, PhCH2CH2CH2Ph), 7.15 (broad, 2H, aromatic-H), 7.34 (broad, 8H, aromatic-H). 13C NMR (CDCl3, 75.5 MHz): δ = 14.11, 22.57, 29.31, 31.46, 31.59, 32.72, 35.30, 128.12,

129.33, 130.98, 137.55, 139.52, 140.60, 140.70.

EA (C33H42)n Calcd: C 89.80, H 10.20;

(439)n Found: C 88.73, H 09.58.


159

1,6-Bis(4-bromophenyl)hexane (130)

Br

Br To a solution of 1,6-bis(4-bromophenyl)hexane-1,6-dione 129 (1.0 g, 2.35 mmol) in dry CH2Cl2

(15 mL) and tris(pentafluorophenyl)borane (0.12 g, 0.23 mmol %) was slowly added

polymethylhydrosiloxane (21.37 g, 9.43 mmol) at room temperature. After 10-12 min of stirring,

vigorous effervescence were observed. The solvent was evaporated and the reaction mixture was

dissolved in hexane and filtered through a pad of silica gel using hexane as eluent.

Yield: 0.86 g (91%).

Poly[(phenyl-4-biphenyl- 1,6-hexa-4,4’-diyl] (131)

n Synthesis method E (see 5.2.1): Dibromo monomer 130 (0.502 g, 0.12 mmol), 1,4-di(1,3,2-



Yield: 0.382 g (97%) insoluble white powder.

Polymer (135)

O n




Yield: 0.398 g (94%) insoluble dark blue colored powder.


160

Poly[1,4’’’-(2’,3’,4’,5’-tetraphenylquaterphenylene] (138)

n




Yield: 0.43 g (98%) insoluble white precipitate.

1,4-Dibromo-2,3,5,6-tetraiodobenzene (140)

Br Br

I I

II

To a 100 mL three-necked flask, orthoperiodic acid (15.46 g, 67.82 mmol), conc. sulfuric acid

(150 mL) and iodine (44.11 g, 173.80 mmol) were added. After 40 min at room temperature, 1,4-

dibromobenzene 139 (10.0 g, 42.39 mmol) was added and the resultant mixture was stirred at

ambient temperature for two days. The reaction mixture was poured into ice-cold water followed

by an addition of saturated NaHSO3 solution (500 mL). The precipitate was filtered and the

filtrate was washed with water (100 mL), ethanol (100 mL), ether (50 mL), and cold benzene (50

mL) to give 25.47 g of a crude product. The product was purified by recrystallization from THF.

Yield: 24.00 g (78%) as a yellow solid.

M. p. 371-372 °C.

MS (EI, 80 eV, 180 °C): m/z (%) = 739.45 (1.11) [M]+.

EA C6Br2I4 Calcd: C 09.75,

(739.45) Found: C 09.94.


161

2,5-Dibromo-3,,6-bis(phenylethynyl)terphenyl (142)

Br Br

To a degassed solution of (2.0 g, 3.00 mmol) of compound 140, Pd(PPh3)4 (62 mg, 0.036 mmol)

and CuI (60 mg, 0.32 mmol) in 15 mL of THF was added under a nitrogen diisopropylamine

(137 mg, 1.52 mmol) followed by phenylacetylene (1.48 mL, 13.5 mmol) and the mixture was

heated under reflux for 2 days. After 200 mL of 1 N HCl was added, the reaction mixture was

extracted with ether (3 ×100 mL). The combined organic layer was washed with saturated

NaHCO3 solution (50 mL) followed by brine (100 mL), and dried over MgSO4. The solvent was

evaporated and the residue was chromatographed on silica gel (eluent: hexane/toluene = 10/1).

The product was purified by recrystallization from ether.

Yield: 0.778 (47%).

MS (EI, 80 eV, 180 °C): m/z (%) = 587.68 (0.84) [M]+..

2,5-Dibromo-3,4,6-tris(phenylethynyl)biphenyl (143)

Br Br

MS (EI, 80 eV, 180 °C): m/z (%) = 613.55 (54.32) [M]+.

Poly[2,3,5,6-(tetraphenyl)-4,4’-biphenylene] (146)

n


162





Poly[2,3,5,6-tetrakis(hexyloxy)-4,4’-biphenylene] (151)

O

O O

O

n

Synthesis method E (see 5.2.1): 1,4-Dibromo-2,3,5,6-tetrakis(hexyloxy)benzene 150 (0.509 g,

0.78 mmol), 1,4-di(1,3,2-dioxaborinan-2-yl)benzene 45 (0.195 g, 0.78 mmol), NaHCO3 (1.0 g),



5.3. Spectroscopic quantification of Pd impurities in polymer 101 Two different calibration sets of experiments were first performed with a known amount of

palladium containing nanoparticles, one without any polymer (Figure 45) and one in the presence

of polymer 101 (Figure 46). Corresponding absorbance versus palladium catalyst measurements

allowed a calibration for quantitative determination of the catalyst present as impurity in the

polymer synthesized.


163

400 500 600 700 800 900 10000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Pd[P(p-tolyl)3]3

a

OD

( I=

1 c

m)

wavelength, nm

Catalyst:

30.00 mg/L = 29.42 μM20.26 mg/L = 19.87 μM11.91 mg/L = 11.68 μM 4.86 mg/L = 4.77 μM

Ligand + catalyst in THF, 25 °C

0 5 10 15 20 25 30 350.0

0.1

0.2

0.3

0.4

0.5

Catalyst: Pd[P(p-tolyl)3]3b

λmax = 795 nm

Ligand + catalyst in THF, 25 °C

OD

(l =

1 c

m) a

t 795

nm

concentration, mg/L

Figure 45. a: Calibration curves without polymers. VIS absorption spectrum of the Pd-ligand

complex; b: absorbance at 795 nm vs concentration of catalyst. (Catalyst: Pd[P(p-tolyl)3]3,

Ligand: N,N-diethylphenylazothioformamide).

400 500 600 700 800 900 10000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Pd[P(p-tolyl)3]3

a

OD

(I=

1 cm

)

wavelength, nm

catalyst:

60.00 mg/L = 58.84 μM 38.81 mg/L = 38.07 μM24.60 mg/L = 24.13 μM11.54 mg/L = 11.54 μM

Polymer 101 + ligand + catalyst, 25 °C

0 10 20 30 40 50 600.0

0.1

0.2

0.3

0.4

0.5

0.6

Catalyst: Pd[P(p-tolyl)3]3b

OD

(l =

1 c

m)

at 7

96 n

m

concentration, mg/L

Polymer 101 + ligand + catalystin THF, 25 °C

λmax = 796 nm

Figure 46. a: Calibration curves with polymer 101. VIS absorption spectrum of polymer 101

with Pd-ligand complex; b: absorbance at 795 nm vs concentration of polymer 101. (Catalyst:

Pd[P(p-tolyl)3]3, Ligand: N,N-diethylphenylazothioformamide).

In both experiments the ligand/catalyst molar ratio was maintained constant at 10 and in the

second experiment, the polymer: catalyst ratio was 100:60 (w/w). The UV/VIS measurements

were carried out with different catalyst concentrations to determine molar absorption coefficient.

Figure 45b and 46b showed corresponding molar extinction coefficient determinations. The value

obtained for experiments without any polymer is, ε (795 nm) = 14,100 ± 200 M-1cm-1 and for the

experiment with polymer 101, ε (796 nm) = 10,100 ± 700 M-1cm-1.


164

For the quantification of the possible palladium impurities in polymer 101, the following

considerations are relevant. For the polymerization reaction to prepare polymer 101, 1 g of

dibromo monomer (3.2×10-3 mol) and 0.019 g of Pd[P(p-tolyl)3]3 catalyst (1.86×10-5 mol) were

used. If all the catalyst would have been present in the polymer 101 formed (100 % conversion of

the monomers), 19 mg catalyst would have been present per 3.2 mmol repeating units (718 mg),

i. e. 2.58 wt %. In a solution containing per liter, 100 mg of the polymer 101 product (polymer +

catalyst), there should be maximally 2.58 mg catalyst per liter: 2.58 μg/ml.

The actual catalyst content in the polymer 101 produced was determined by following

procedure described by Nielsen et al.[98] 10 mg polymer 101 product was dissolved in 10 ml

THF, followed by the addition of 2.55×10-6 mol ligand, and a 1:1 (v/v) dilution with THF. The

absorption spectrum in the VIS-range was then recored (see Figure 47).

400 600 800 10000.0

0.2

0.4

0.6

0.8

1.0a

OD

(I=

1 cm

)

wavelength, nm

Polymer 101 + ligand inTHF, 25 °C

600 800 10000.000

0.002

0.004

0.006

0.008

0.010

b

OD

(I=

1 cm

)

wavelength, nm

Figure 47. a: VIS spectrum of polymer 101 after treatment with ligand in THF, 1:1 dilution

(v/v); b: zoom in around 800 nm.

If all palladium catalyst used would have been present in the polymer 101, (12.9 mg/L diluted

solution = 1.28×10-5 M), the absorbance at 796 nm should have been 0.129 (with ε = 10,100 M-

1cm-1, see Figure 47).

This would correspond to 0.6 mol % (= 2.58 wt %) catalyst present in the polymer: 2.58 mg

catalyst/100 mg polymer (= 25,800 ppm (w/w): 1 ppm (w/w) = 1 mg in 106 mg, 1 wt% = 1 mg in

100 mg i.e 104 mg in 106 mg = 104 ppm (w/w) = 10,000 ppm (w/w)).

With the spectroscopic measurement described, one could have detected a peak with an OD (l = 1

cm) > 0.005, corresponding to 1032 ppm. Since there was no such peak, one can conclude that

the catalyst content in the polymer sample was below ≈1,000 ppm (= 0.1 wt % = 0.023 mol %).


165

Without dilution and with more polymer one may decrease the detection limit to ≈ 500 ppm

(w/w). For lower Pd-contents and for the determination of „bound“ Pd, the spectrophotometric

method is not sufficient.

Chapter 6 References

166

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Appendix

Symbols and Abbreviations b.p. boiling point

br. broad signal (NMR)

BuLi n-butyl lithium

calcd calculated

cps count per second

d doublet (NMR)

DCC dicyclohexylcarbodimide, C6H11N=C=NC6H11

dd doublet of doublets (NMR)

DEAD diethyl azodicarboxylate

DIAD diisopropyl azodicarboxylate

DMF dimethylformamide

DMSO dimethyl sulfoxide

DSC differential scanning calorimetry

EA elemental analysis

EI electron impact

EI-MS electronic impact mass spectroscopy

ESI-MS electro spray ionization mass spectrometry

δ chemical shift downfield from TMS, given as ppm

ε molar absorption coefficient

g gram

GPC gel permeation chromatography

h hour(s)

HRMS high resolution mass spectrometry

H Hertz (sec-1 or cycles per second)

175

ICP-MS inductively coupled plasma mass spectroscopy

J coupling constant, in Hz

λ wavelength in nm

LS light scattering

m multiplet (NMR)

M molar

[M]+ molecular peak (MS)

MALDI-TOF matrix assisted laser desorption/ionization- time of flight

m/e mass-to charge ratio in mass spectrometry

mg milligram

MHz, megaHertz = 106 Hz

min minute

mL milliliter

mmol millimol

Mn number average molecular weight

m.p. melting point

MS mass spectrometry

Mw weight average molecular weight

μg microgram

nm nanometer

NMR nuclear magnetic resonance

OWLS optical waveguide lightmode spectroscopy

OEO oligo(ethyleneoxy)

PC polycarbonate

PMMA poly(methyl methacrylate)

PD polydispersity

176

Pn number average degree of polymerization

ppm parts per million

Pw weight average degree of polymerization

PPh3 triphenyl phosphine

PMP poly(meta-phenylene)

PPP poly(para-phenylene)

RSD relative standard deviation

r.t. room temperature

r.u. repeating unit

s singlet (NMR)

SCC Suzuki cross coupling

SPC Suzuki Polycondensation

t triplet (NMR)

tBu tert-Butyl

TBAB tetrabutyl ammonium bromide

TEA triethylamine

TGA thermogravimetric analysis

THF tetrahydrofuran

TLC thin layer chromatography

TMEDA N,N,N´,N´-tetramethylethylendiamine

TMS trimethylsilyl

UV ultraviolet

WAXS wide-angle X-ray scattering

177

Curriculum Vitae • Personal Details: Name : Ramchandra Maruti Kandre Address : At- Anaphale, Post- Mayani Tal- Khatav, Dist- Satara Maharashtra, India 415102 Phone: +91-2161- 270636 Email : [email protected] Date of Birth : May 9, 1978 Marital Status : Married Nationality : Indian • Educational Details:

Ph.D. Syntheses and Characterization of Amphiphilic, Water Soluble

Poly(p-phenylene)s and High-Tg, Tough Poly(m-phenylene)s

by Suzuki Polycondensation

ETH Zürich 8093, Switzerland.

Feb 2003-

June 2007

M.Sc. (Organic Chemistry) from University of Pune (INDIA)

in May 2000 with Distinction (75.70 %), 2nd rank in the

University. 1998-2000

B.Sc. (Chemistry) from Shivaji University (INDIA)

in May 1998 with Distinction (81.83 %), 2nd rank in the

University. 1995-1998

H.S.C. Higher secondary certificate

Balvant College, Vita Tal- Khanapur, Dist- Sangli, 1993-1995

S.S.C. High School, Secondary School Certificate

Bharatmata Vidyalaya, Mayani Tal-Khatav, Dist- Satara 1987-1993

• Additional qualification:

SET (State Eligibility Test) Examination Qualified conducted by University of

Pune, Government of Maharashtra, INDIA in May 2000.

178

• Research Experience:

• Six years research experience in synthetic organic chemistry as well as in

supramolecular chemistry.

• I worked as a research student on GE project in National Chemical Laboratory

(NCL) Pune, INDIA from Oct 2000 to Oct 2002.

• Awards/ Scholarship:

• Secured Prize in H. J. ARNIKAR Competition conducted by Pune University in the

year 2000.

• EKLAWYA fellowship awarded by Government of India for the year 1998-2000

during post-graduation.

• List of Publications:

1. Ramchandra Kandre, Kirill Feldman, Han E. H. Meijer, Paul Smith, A. Dieter

Schlüter. Suzuki polycondensation put to work: A Tough poly(meta-

phenylene) with a High Glass-Transition Temperature. Angew. Chem. Int. Ed.

2007, 46, 4956-4959.

2. Giacomo Bergamini, Paola Ceroni, Vincenzo Balzani, Maria D. M. Villavieja,

Ramchandra Kandre, Igor Zhun, Oleg Lukin. A photophysical study of

terphenyl core oligosulfonimide dendrimers exhibiting high steady-state

anisotropy. ChemPhysChem 2006, 7(9), 1980-1984.

3. Oleg Lukin, Volker Gramlich, Ramchandra Kandre, Igor Zhun, Thorsten Felder,

Christoph A. Schalley, Grigoriy Dolgonos. Designer Dendrimers: Branched

Oligosulfonimides with Controllable Molecular Architectures. J. Am. Chem.

Soc. 2006, 128(27), 8964-8974.

4. Ramchandra M. Kandre, Fabian Kutzner, Helmut Schlaad, A. Dieter Schlüter.

Synthesis of high molecular weight amphiphilic polyphenylenes by Suzuki

polycondensation. Macromol. Chem. Phys. 2005, 206(16), 1610-1618.

179

5. Ramchandra M. Kandre, Helmut Schlaad, A. Dieter Schlüter. Amphiphilically

equipped poly(para-phenylene)s with the potential to segregate lengthwise.

Am. Chem. Soc., Polym. Chem. Div., Polymer Prepr. 2004, 91, 406.

• Posters: 1) Ramchandra M. Kandre, Kirill Feldmann, Paul Smith, Hans E. H. Meijer,

A. Dieter Schlüter.

“A new family of high performance polymers by Suzuki polycondensation”

Spring meeting “High Performance Polymers”, June 8, 2007. CIBA Specialty

Chemicals Basel, Switzerland.

2) Ramchandra M. Kandre, Kirill Feldmann, Paul Smith, A. Dieter Schlüter.

“Novel synthetic developments in Suzuki polycondensation”

Fall meeting of the Swiss chemical society. Octomber 13, 2006 University of

Zürich, Irchel campus Zürich, Switzerland.

3) Oleg Lukin, Volker Gramlich, Ramchandra Kandre, Igor Zhun.

“Dendritic oligosulfonimides with controllable molecular and supra-

molecular architectures”

Abstracts of Papers, 232nd ACS National Meeting, San Francisco, CA, United States,

September 10-14, 2006.

4) Ramchandra M. Kandre, Kirill Feldmann, Paul Smith, A. Dieter Schlüter.

“Novel synthetic developments in Suzuki polycondensation”

15. Vortragstagung der GDCh-Fachgruppe Liebig-Vereinigung für Organische

Chemie vom 7. bis 9. September 2006 in Bad Nauheim.

5) Ramchandra M. Kandre, A. Dieter Schlüter.

“Synthesis of ionic and nonionic amphiphilically equipped Polyphenylenes by

Suzuki polycondensation”

American Chemical Society (ACS) - Council of Scientific & Industrial research

(CSIR) joint conference at NCL, Pune (INDIA) on Jan 7-9, 2006.

180




PGS 2005 Fall Meeting Science in Suisse Romande Romande November 18, 2005.




12th International conference on Boron Chemistry IMEBORON-XII Sep 11-15, 2005,

Sendai, JAPAN.

8) Ramchandra Kandre, A. Dieter Schlüter, Helmut Schlaad.

“Amphiphilically equipped poly(para-phenylene)s with the potential to segregate

lengthwise”

Abstracts of Papers, 228th ACS National Meeting, Philadelphia, PA, United States,

August 22-26, 2004.

• Oral Presentation:



National Chemical laboratory, Pune (INDIA) on January 5, 2006.

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